It's difficult to perform perfectly season after season unless you're Lionel Messi or Cristiano Ronaldo, but some players just haven't been up to their usual standards this campaign.
Sometimes having a brilliant season in the previous term can be a detrimental thing... the expectation is that much more, the bar raised that much higher for the next.
Some players have made big money moves and have price tags to justify, other go off the boil.
This season has had its fair share of standout and break-out performers, but it's also had its fair share of lackluster efforts.
Here is a list of the goalkeepers and defenders who have disappointed most this season:
GK - Joe Hart (West Ham United)
The West Ham United loanee often comes under the microscope for his performances, particularly after being England's number one choice for such a long time.
After arriving at Manchester City at the beginning of last season, Pep Guardiola made it clear that Joe Hart wasn't in his vision and the picture at City so long as he was in charge.
Hart was then loaned out to Serie A outfit Torino where the English media watched his every move.
A torrid Euro 2016 campaign followed Hart around like a bad smell, and he got off to a rocky start in Italy, being culpable for costing his side and losing points.
Hart returned at the end of the campaign to find himself out of favour once more after the acquisition of Ederson Moraes.
At West Ham, this season, Hart's performances have been questionable. So much so that he was dropped after a 4-0 drubbing away at Everton and had to play second fiddle to backup Adrian until the unforgettable 0-3 home loss to Burnley.
With the World Cup looming, it's been another season to forget for Hart as his starting position for the Three Lions is looking in serious doubt.
Serge Aurier (Tottenham)
After arriving at Tottenham at the end of the summer transfer window, many expected Aurier to add a new dimension to a defence that had just lost Kyle Walker.
However, despite costing Spurs a fee of around £23 million, he's yet to catch fire in the way the club and their fans would have hoped.
The form of alleged understudy Kieran Trippier has kept the Ivorian out of the side, but the opportunity was there to be taken - and he hasn't.
Such is the gap in form between Aurier and Trippier, that Aurier has been limited to making only 17 league appearances, of which only 14 were starts.
With Spurs' plethora of reliable options at fullback on both flanks, playing time is never guaranteed. If Aurier is to make his mark in England, he must raise his game for next season.
Michael Keane (Everton)
It's been a rather inconsistent, turbulent season for Everton.
Defensively the Toffees have been poor. They've conceded 55 goals this campaign, which is 11 more than last, with a game still remaining.
After pulling up trees for Burnley last term, Keane was eager to move on as Everton came in for his services; paying an initial £25 million.
Keane was expected to slot in comfortably in a usually tight defensive unit. As the season has developed though the selection often changed, and Keane was playing alongside a mixture of Phil Jagielka and Ashley Williams (who has also had a sub-par season).
Keane played in his part in Burnley side that kept ten clean sheets in the last campaign, his Everton team have only seven, this.
Kevin Wimmer (Stoke City)
This season has been such a disaster for Stoke City that anyone of their regulars could be in the firing line here.
Wimmer however, given his hugely touted potential and promise, takes the plaudits. Having been on the fringes of Tottenham's starting line-up, and impressing there when given a chance, it was hoped by then-manager Mark Hughes that Wimmer would form a formidable partnership with loanee, Kurt Zouma.
The season and the move couldn't have gone worse for Wimmer, though, and he's spent most the season on a personal fitness regime and having to settle for the odd game for the development sides.
At £18million, Wimmer will probably be touted as one of the transfer flops of this season. Manager Paul Lambert isn't keen on the Austrian, and it'll be interesting to see how his future takes shape over the summer.
Shkodran Mustafi (Arsenal)
Taking the hit for a terribly sub-par Arsenal defence this term is Shkodran Mustafi.
The Gunners knew they were out of contention for a top-four spot weeks ago, but they sit a staggering 12 points behind Liverpool in fourth - alarming.
Their defence this season has been uncharacteristically poor, that they've conceded almost twice as many goals as the Manchester clubs, and 19 more than bitter rivals Tottenham, with one game still to play.
The back four has been a problem area for Arsenal in recent seasons as they saw their customary grip on Champions League qualification slip last term, and this season, it's got worse.
Mustafi, who has been charged with most of the senior responsibility in the absence of Laurent Koscielny, hasn't lived up to his billing.
His poor form has seen him relegated to the bench in recent weeks and has seen the likes of Calum Chambers and Kostas Mavropanos starting in his place.
Jack Butland (Stoke City)
Stoke City and Jack Butland have endured a torrid season. The England stopper's form has brought his World Cup selection in question.
John Stones (Manchester City)
After being touted as England's next-best thing, John Stones' career hasn't yet really got going. He's endured a couple of spells on the sidelines this season through injury, but can't seem to hold down a regular starting spot in City's line-up. Sooner or later Stones will need to start moving on his potential, another wasted season.
Have we missed anyone out? Let us know in the comments section below.