It's not between the ears - it never has been, and it never will be. In fact, anyone you're paying good money to teach you or coach you in this game, that tries to convince you that it is between the ears, is wasting your money...big time.
Of course, you need to concentrate - that's essential in any endeavor - but at the end of the day, tennis is not chess: the ball, the court, the racquet, and the other guy, all impact how you play the game, and the results you get. And while those of us who follow tennis intensely (or otherwise) are inclined to focus our evaluations on the big 4, one need only take the curious case of Nico Almagro to see how a player, that had so much going for him, has technically stagnated for 3 years, and as a result, his window of opportunity to make a major impact in the game just may have closed.
Not locked, but definitely closed for now.
Six years ago I extolled the virtues of this swashbuckling, bomb throwing, preening man from Murcia, after watching him bull fight his way to two titles in succession in Costa Do Sauipe and Acapulco. And while any number of players have gone on a hot streak at some point in their careers, there was something about the way he won those titles that made me think we could have been looking at one of the next stars of the game. He didn't just have a good serve, he had one of the best serves on tour. He didn't just have a good forehand, it had variety with the ability to dynamically inject pace into the rally at almost any moment. And that backhand...man, is that ever a beautiful backhand.
And he seemed to have the one element that the pundits place greater value in than any other - balls. Big, elephant balls to go with a big game. When the moment called for a howitzer serve, he delivered. A backhand down the line? No problemo. Not always, of course - he missed those shots as often as he made them, but that in and of itself is better than the vast majority of tennis players, and can be the difference when it is needed to pull out matches that seem out of reach: the ability to put the point, the game, the set and the match on your racquet.
But since then, there's been something missing from his game.
Take a look at the career progression of some of his contemporaries - Wawrinka beefed up his forehand, and improved his volleys, and won the Australian Open this year. Berdych developed a passable (not even good, just passable) net game, also beefed up his serve and suddenly he's more often getting results when he should, than he did in the past, and is a perennial top-10 player. Gasquet has improved his fitness, hits his forehand with a little more purpose, and even though he regularly stands 8-12 feet behind the baseline, still finds his way to the net from time to time, and he too is in the top 10. Tsonga's fitness, always a question mark for the first half of his career, is no longer a serious issue, and he is now more capable of bringing to bear the full suite of skills he is blessed with, resulting in him consistently justifying his seeding and winning the odd title here and there. Even David Ferrer, known essentially as a grinder, has beefed up his serve, plays closer to the baseline, and reached his first major final at Roland Garros last year...and Almagro has one more clay title in his treasure chest than he does.
But what improvements has Almagro truly made in the last 3 years?
His serve is still a howitzer, and he often finds himself near the top of the ATP leader board in aces, but somehow his serve game win percentage is rarely in the top 10. One could point to any number of factors for this, but I think the most telling is the fact that aside from pace, there's very little to his first serve. In order for it to be effective, he's got to hit it like a ton of bricks...all the time...and that usually results in a low first percentage. Combined with his generally erratic play, he is unable to muster the consistency needed to compensate for the tactical frailty of his serve, and his return games suffer from the burden.
His backhand is still beautiful to behold - along with Wawrinka and Gasquet, it's one of the best on tour when he comes over it. But the slice is an atrocity - soft, slow, and with way too much net clearance, he doesn't use it enough to give his opponents the problem of dealing with variety, it doesn't have the bite to keep his opponents from attacking it, and he never uses it to come forward...never.
Speaking of which, the only thing worse than his slice backhand is his net game. A weak and inconsistent overhead causes him to set up too far away from the net to consistently finish points there. His poor volleying technique (from the grip to his point of contact) and the lack of familiarity with covering the angles, means that he is more likely to lose the point when he comes forward than win it. That's a tactical paradox, and a recipe for playing further and further behind the baseline, which is never good.
Speaking of which, his court positioning may work on a clay court, but the moment he plays someone who defends better than he does (which isn't saying much, because he's not the quickest guy on tour, nor does he have particularly efficient footwork) or someone who stands on top of the baseline and dictates, he's lost the plot. Modern tennis is such that even the best movers on tour can't survive conceding the baseline for long, and Almagro has never been known for his movement.
Finally, that forehand - he used to hit it flatter from time to time, when the situation called for it tactically. These days, his forehand is just a tool to keep him in the point, rarely hit for winners or pressure, and often landing short in the court, with a good deal of spin, but not nearly enough to keep the pressure off of himself. This just isn't going to get it done. Murray used to spin the forehand in for the most part, but one of the key components of his game that has improved over the last 3 years is the power and direction of his forehand, and his ability to dictate with it.
No such improvements with Almagro.
If ever there were a case of a player who has stagnated technically, and whose career has stagnated as a result, it's Almagro. And while the pill-pushing charlatans of the tennis punditry will have you believe that his problem is between the ears, I would argue that the symptom is between the ears, but the cause is what he does, or more accurately doesn't do when he practices.
Namely, improve his game.