Chief among them was an obvious and frustrating lack of consistent service to Romelu Lukaku, a player forced to carry the weight of expectation and responsibility for goals on his young shoulders – he wouldn't turn 22 until the final week the campaign – and who became an easy target for criticism in a dysfunctional team struggling for goals. Often isolated in a lone-striker, target-man role to which he looked wholly unsuited despite his muscular frame, he was dropped for a period – much to his understandable chagrin –  when the Blues' already iffy form nose-dived over last year's Christmas period.
If rediscovering some of his own self-motivation in the early weeks of 2015 was part one of the equation for the Belgian,  the other would be service. The arrival on loan of Aaron Lennon in February coupled with Arouna Kone's incrementally improving fitness helped but service to the big  man remained at a premium in the Premier League. Lukaku profited in the Blues' hectic FA Cup Third Round tussle with West Ham and the more open nature of Europa League football, scoring nine goals in six cup matches, but managed just four in the remainder of the league season, half of those from the penalty spot.
No wonder, then, that Evertonians rejoiced when Martinez made the acquisition of a creative No.10 capable of feeding his £28m striker as his main priority for the summer and then sulked when that potential “saviour” failed to materialise before the transfer window closed.
It's unlikely he knew to what degree at the time but Martinez would go a long way to solving Lukaku's problems in July when he pulled off what could prove to be the bargain of the season. The completion of Kone's recovery from a career-threatening knee injury and emergence as a reliable asset up front, Â together with Ross Barkley's own renaissance after a difficult 2014-15 campaign of his own, has helped transition Everton's attack from under-manned and erratic to dynamic and potent this term. But it was the acquisition of Gerard Deulofeu on a permanent transfer from Barcelona for just £4.2m that has been the real difference-maker so far.
With no first-team level striker arriving in the most recent transfer window, it meant that either Kone would need to become a more impactful player or the manager would need to find a way of supplying his Belgian talisman more consistently if 2015-16 wasn't to go the same way as the previous campaign. Pleasingly, Evertonians have seen some of both. Kone has shown at times that he can be a valuable foil for Lukaku as a second striker, occupying opposition defenders and giving the Belgian space in which to operate less as a target man and more as a threat either with the ball in front of him or playing on the shoulder of the last man.
And Deulofeu has added a vital blend of flair, unpredictability, pace, vision and desire to get balls into the danger areas, to the point where fans have gone from lamenting a side that was ponderous, and seemingly bereft of attacking ideas to celebrating one often brimming with confidence and invention going forward. Aided further by Barkley's rejuvenation after what was a difficult sophomore season as a full-time member of the senior side, the Spanish wizard has breathed new life into the team and changed the character of Everton's attacking make-up.  Lukaku, of course, has surpassed last season's Premier League's tally of goals in just 15 games, with Deulofeu – the striker has nicknamed "The Supplier" – laying on half of them. He has been, thus far, the “x” factor so badly missing from the Toffees' team.
Despite his natural talent, nothing about the Masia graduate's impact either in his first year at Goodison Park or this season was a given. Indeed, anyone who saw a petulant Deulofeu sulk his way through the difficult pre-season exhibition game against Valencia in Miami in the summer of 2013 or his father-and-scolded-son-esque exchange with Martinez in the stadium's tunnel after that 1-0 defeat might have wondered how easily he could integrate into a foreign club.
And while his displays during his ensuing loan spell captured Everton imaginations and gave birth to the #HesMagicYaKnow hashtag on social media, he was a raw and mercurial presence who made more appearances from the substitutes' bench than as a starter. The defensive side of his game was an obvious weakness but was offset by his explosive ability and desire to run at defenders at the other end of the field.
That yin and yang between his talent and his flaws was surely reflected firstly in the comparatively small fee Everton were able to negotiate for the 21 year-old's services — Barcelona's buy-back clauses notwithstanding — and then in the belief among some Everton supporters that signing him represented something of a punt on an unreliable player whose career had been derailed from the fast track to stardom he appeared to be on with the Continent's biggest club.
Deulofeu was coming off the back of a hugely disappointing loan spell with Sevilla and, still not deemed ready for Barça's first team, was facing the prospect of a third successive season-long loan away from the Nou Camp. After spending 2013-14 broadening his horizons with Everton, his year in Andalusia was designed, no doubt, to refine his skills back in La Liga in preparation for finally graduating to Barcelona's first team.
Instead, far from being the ideal homecoming, Deulofeu's season at the Ramón Sánchez Pizjuán Stadium would become a frustrating one. Rather than being  an inspirational presence in Sevilla's successful defence of their Europa League crown and fourth-place finish in La Liga, the winger would find himself watching on from the sidelines in the latter half of the campaign and he left at the end of it with manager Unai Emery's critical words ringing in his ears.
“He has incredible qualities but lacks others. Put him out there, one on one and ... pfff,” Emery told The Guardian's Sid Lowe before the Europa League Final in May. “But make him play football with teammates, on a big pitch, and it's hard. He doesn't have the maturity or capacity for sacrifice yet."
Many observers of Deulofeu's rapid and exciting rise through the ranks at La Masia, Barcelona's celebrated academy, weren't unduly surprised. Ever since joining Barça as a promising nine-year-old, the Riudarenes-born player had been regarded as “the next big thing” from a club renowned for churning out glittering stars. He had a boot deal by the time he was 12, Nike endorsements by 14 and was, by the time he graduated from Barcelona B, being labelled as the new Cristiano Ronaldo and a future Ballon D'Or winner on the basis of his pace, quick feet, mesmeric step-overs and goal-scoring ability. His prodigious talents allowed him to jump age groups and, much like he is doing for Spain U21s today, he was scoring hat-tricks for fun in Spain's second division.
Luis Enrique, the man who helped nurture him in the final phase of his development through the Balugrana's youth ranks but ended up letting him go this past summer once remarked: "Who stood out from my Barça B team? Deulofeu is the stand out. He's got speed, he can beat a player and score goals."
Ahmed Shahin, BarcaBlaugranes.com
However, as Gerard now admits, all the attention inevitably went to his head a little and he no doubt felt that his progression to the senior side was almost pre-ordained. Like many of his peers in Barça's academy — Rafinha, Bojan Krkic, Hector Bellerin, Marc Muniesa, Oriol Romeu and Adama Traore among them (all but one are now in England's Premier League, of course) — and even Mikel Arteta and Jordi Gomez before him, however, he found the step up from the Mini Estadi to the first-team, where the best of the best ply their trade, a mammoth one. Not only was his path blocked by none other than Lionel Messi, Luis Suarez and Neymar but the enormous and constant pressure to win trophies at the Nou Camp meant that Enrique could ill-afford to take a chance on an under-developed prospect, no matter how glittering his pedigree.
While Enrique's plan to farm him out on loan for a third time this season might have been an attempt to kick the proverbial can down the road and see where the now 21-year-old's development stood in the summer in 2016, Deulofeu yearned for stability and had no interest in another temporary assignment, even if meant staying in Spain and remaining a Barcelona player. He says that once it was clear that Martinez wanted him back at Goodison, there was only one choice for him: he wanted to go back to his adopted home on Merseyside.
Regardless of what his spell in Sevilla appeared to say about his career track, the logic of Deulofeu's sale to Everton was not universally accepted by Barça's fans, the candidates for the club's presidency at the time or the local media. And his “failure” to make the grade at the  Nou Camp has been held up as emblematic of what is wrong with what some regard as the Catalan giants' failing academy.
As the Barça Blaugranes blog put it prior to Gerard's transfer to Goodison:
ÂFor so long La Masia has been considered to be the holy grail of youth development in football, but with many talents having been wasted, there is a need to establish whether this is the case.
There is no doubt Gerard Deulofeu is one of the most talented footballers contracted to FC Barcelona, but he has his flaws. He is arguably the human epitome of La Masia.
At the time Deulofeu signed a permanent deal with the Blues, Lluis Mascaro of Sport expressed his disbelief:Â "I cannot understand that a player who has generated such frenzy for Barcelona, with his talent and image, is 'deleted' in this way by the team."
Barça's decision was, of course, Everton's gain and it's become clear in fairly short order how mutually beneficial Deulofeu's return to Everton has been. The player himself earned a special place in Evertonian hearts during his first season wth the club and supporters on Twitter, for example, never let him forget it, keeping alive the flame of affection throughout his time in Seville. Small wonder then that he made a beeline for Goodison once it became clear that the Blaugrana were willing to sell him.
And if his impact was a little delayed – he didn't start a game until the latter half of September but, just as he did two seasons prior, announced himself in the League Cup with two assists in a win over Barnsley – his reunion with Lukaku would blossom in a pulsating Premier League win at West Bromwich Albion the following week where the Spaniard laid on two goals for the Belgian striker.
Theirs is now a goalscoring combination that has made Everton one of the most exciting attacking teams in the Premier League. Lukaku is, at the time of writing, the second-highest scorer in the top flight and half of his 15 goals have come by way of assists by Deulofeu. Key to that dynamic has been the variation in the Spaniard's approach; where two years ago he would routinely drive to the byline and try to thread square balls into the six-yard box, now he has discovered a wonderful range of deliveries. Most deadly is an ability to bend wicked balls behind or over defenders from deep – even better, he is able to disguise the timing and the intent of these crosses – or dissect a defence straight down the middle with perfect weight for Lukaku to race through and score.
It's that unpredictability, coupled with a defender's worst nightmare of a pacy winger prepared to run straight at you, that makes Deulofeu's addition to the team so exciting. He has only enhanced the Toffees' potency on the counter-attack and while Kevin Mirallas's morale has fallen away in tandem with his appearances tally, Deulofeu is providing a hungry, youthful exuberance and a threat in terms of goals and free kicks in the out-of-favour Belgian's stead. Best of all, while he still has so much more to learn, he is enjoying the most productive period of his fledgeling career to date and is demonstrably improving the defensive side of his game which will be vital to his success in England.
Deulofeu's eye-opening re-introduction to the Premier League has, inevitably, raised fears among Everton fans that Barcelona could activate the insurance policy on their homegrown talent as soon as next summer. In return for the bargain price Everton paid for him last July, the Blaugrana successfully negotiated a staggered repurchase clause whereby they could buy the player back at the end of this season for €9m or the summer of 2017 for €12m. Both are paltry sums in today's transfer market that seemed reasonable enough while the prospects of his success back at Goodison were still unknown but are now making Blues fans very nervous.
They can probably rest easy for the time being. First of all, for all of Deulofeu's wonderful abilities, he remains an uncut diamond – precocious but still immature in parts of his game; developing nicely but with lingering flaws in his attitude and consistency. That much of his game relies on the element of surprise and the hopeful means that a lot of what he tries doesn't come off and there are times when his performance on a given day can deteriorate into ineffectiveness if he loses confidence in his ability to affect a game. In that sense he is far from a "90-minute player" at the moment; he can delight and frustrate in equal measure... although the flip side is that he often just needs to produce one or two moments of successful magic in a match to decide it.
That immaturity of temperament is another reason why his boyhood club might not be as ready to bring him home as the tabloid speculation will have you believe when they're seeking to fill column inches next year, particularly if Deulofeu is added as a wildcard in Spain's Euro2016 squad. His propensity to throw himself to the turf at the slightest contact already seems to have marked his card with Premier League referees and garnered him the kind of reputation for theatrics that has plagued other Continental stars like Ronaldo.
As Bill Haisley recently wrote for Deadspin:
Deulofeu retains remnants of that kid who was famous as a teen, heralded as the hottest prospect for one of the world's biggest clubs, a surefire superstar in the making. At times he still carries himself as if he was God's gift to soccer. Thankfully for his own self and fans like me, he continues to transition away from the entitled brat he once was and the finished article he should one day become.
Â
Barcelona legend Charly Rexach, meanwhile, commented back in February that, “Deulofeu is good, but maybe be believes it a little too much.” Despite his years in the glare of the spotlight back in Spain and his travels over the last three seasons, Gerard is still only 21 – he has plenty of time to mature and work those foibles of temperament from his game but until he has he likely won't be regarded as the kind of finished article that could displace the kind of players that would stand in his way were he to return to the Nou Camp in the next year or so.
What is overlooked in discussions about Deulofeu's future, however, is his strengthening bond with Everton Football Club. His ties to Barca and Catalonia will always be strong but his deep affection for Evertonians – and Merseyside in general – and their support of him are probably underestimated by a national media who likely view the winger's stay at Goodison as ephemeral. The Blaugrana will always be his first love but, having wedded himself to the Blue side of Liverpool for the next three years at least, who's to say he hasn't found a better partnership for the long term? Feeling wanted is a powerful thing.
Pep Guardiola
Deulofeu commented recently that he never should have left Everton in the first place and that he hopes to stay at Goodison "for a lot of years." The rationale for his return to Barcelona in the summer of 2014, where he hoped to convince the incoming Enrique that he was good enough to finally step up to the first team at the Nou Camp, was sound on the face of it but he does not look back fondly on his time with Sevilla, a season that he says "represents a bad time for me." Now, he is settled among Spanish expats in England's northwest and, in the words of his manager, "enjoying his football" playing for fans who adore him. "Their passion is my passion,"Deulofeu says of the Goodison faithful. “They live the game in the same way I do.”
The clearer and more present danger might lie in the loss of Lukaku who, thanks in part to the ammunition supplied by Deulofeu, is attracting even more attention having passed the 50-goal mark for Everton in 100 appearances and is a run of having scored in seven consecutive matches in all competitions. The looming dread for Blues fans is that if Everton aren't able to secure Champions League football this season, or qualify for the Europa League at least, then the club may not be able to keep Lukaku at Goodison Park beyond next summer.
Could he be persuaded to stay another year at least if the club don't have a seat on Europe's gravy train next season? The dynamism of his relationship with The Supplier and his role within an exciting, young and evolving team would be a significant pull but the former Anderlecht and Chelsea man is nothing if not ambitious and only he knows just how impatient he is to play on the Continent's biggest stage.
Those questions will continue to nag at the Evertonian psyche in the coming months but in the meantime the fans will get to enjoy one of the most magical partnerships in recent memory, one that could yet deliver something special this season if the team's defensive issues can be sufficiently resolved.
Goodison is an arena that has always appreciated skill and talent – something Deulofeu has in spades; someone to lift bums off seats in anticipation as he flies down the flank, cuts inside or delivers one of those sumptuous crosses to the area in which strikers thrive. In what has been a relatively turbulent start to his professional career, the young Catalan has found a home where he can weave his magic and it's a relationship that is likely to keep the little wizard in Everton Blue for a good time yet.