It's often said, erroneously and lazily perhaps, that the Premier League is a difficult environment to adapt to, and that moving to a big club in it can take time for players to show their true worth.
Obviously that's far from the case with all signings but some certainly have enjoyed ups and downs after arriving to these shores recently.
Here we take a look at eight players signed to the biggest clubs in the league over the past four transfer windows, for whom there is still an element of doubt or uncertainty over how much of a positive impact they will have.
To go along with the consensus of "you get what you pay for", only players who moved for over £10 million were considered and transfermarkt.co.uk was the source for all fees, for comparison and consistency.
Real Madrid to Arsenal, summer 2013
Arsenal's Ozil was signed late in the summer for a club record £44 million and therefore was reasonably expected to hit the ground running and consistently provide quality performances.
With 56 chances created this term, per Squawka, he's one of the top players in the league on that basis, but his recent displays and lethargy have left something to be desired.
Whether because of being used to a winter break or simply suffering a general dip in form, questions have recently arisen about the German which he'll have to get back to his best to answer.
Valencia to Tottenham, summer 2013
Tottenham weren't shy about spending their money earned off the back of the sale of Gareth Bale in the summer, with Valencia's Soldado their key striker signing.
It's fair to say he has massively disappointed so far, with just five goals to his name and most via the penalty spot. Soldado hasn't yet found the net in the league in 2014 and has spent most of the last few games sat on the bench.
He needs to step up big time or be judged a failure at Spurs.
Everton to Manchester United, summer 2013
The curly-haired Belgian midfielder was a massive part of Everton's success, but he has barely impacted on Manchester United this season.
Poor form and injury means he is not really seen by anybody as the answer to their current woes, having played just eight times in the league since his big-money move.
United might have needed a midfielder in the summer but it seemed slightly as though they signed Fellaini simply because they failed elsewhere in the end.
He has a lot of work to do to live up to his big fee and to continue playing for a club of the status of United.
Swansea City to Liverpool, summer 2012
Joe Allen is now approaching the end of his second season at Liverpool and while he has fared well in patches, he certainly hasn't lived up to the billing of the main piece of Brendan Rodgers' rebuilding plans.
Now with the midfield formation settled and a few players having altered their roles within it, one wonders whether Allen will be able to win back a regular place after missing out through injury earlier this season.
Consistency has been his problem so far, unable to maintain his early high standards, and he'll have to impress his boss and the fans an awful lot to become a regular part of the team once again.
Fiorentina to Manchester City, summer 2013
Manchester City summer signing Stevan Jovetic has had to wait to start to make his own impact on the Premier League after early season injuries.
Only now beginning to get a run of appearances, he has managed just one league goal and still looks some way short of match fitness.
There won't be too many who doubt his quality after his time in Italy but all eyes will be on the Montenegrin to see if he can reproduce that talent in the Premier League.
Borussia Dortmund to Manchester United, summer 2012
It often appears as though the ones who mistrust Kagawa's ability the most are those he plays for, his Manchester United managers last season and this.
Many United fans want to see him started more often to give United a creative edge, but it's also worth acknowledging that the Japanese playmaker has not shown his true form when given irregular starting chances for the Red Devils.
He has had almost two years in England but is yet to show he can live up to the hype for his team.
Bayer Leverkusen to Chelsea, summer 2013
Chelsea's wide forward Andre Schurrle started the season in the team but has quickly found himself on the fringes, mainly used as an impact substitute.
He has not really contributed much in terms of quality chances created (18) or goals (three, per Squawka) for the Blues and with the likes of Willian and Eden Hazard ahead of him, it's tough to see him getting a long run of starts any time soon unless he can show those traits off the bench first.
The German has an important role in the squad no doubt, but he will have plenty of eyes on him to see if he can bring the kind of form he was lauded for in the summer.
AS Roma to Tottenham, summer 2013
Our final player is another summer signing for Tottenham, Erik Lamela.
The Argentine had a breakout season with AS Roma last year but has failed to have any kind of impact on Spurs' team this term. In his team's last 13 league games he has totalled just 168 minutes of football, with only six chances created all season, per Squawka.
Lamela is Spurs' record signing and they'll be loathe to let him leave so soon without having some kind of return on the field from their marquee man but so far he's been well off the pace and looks to be largely mistrusted to have an impact.
Advanced statistics courtesy of Squawka.com