iego Costa scored 27 league goals for Atletico Madrid last season, FIFA Coins helping them to lift the La Liga title, so what could possibly make us think that the Spanish international will flop?
It would be unfair to simply make the comparison with the Blues' other big money Spanish striking flop, Fernando Torres. After all, Torres cost £18 million more and lost his form long before Chelsea signed him in January 2011.
One similarity with Torres however is that Diego Costa is coming off the back of a disappointing World Cup with Spain (though that's true of the former World Champions' entire squad) in which he barely made an impact in the three group games. What's more, injury restricted his participation in the closing weeks of the season for Atletico and cutting short a goal-scoring form that had propelled them to the top of the league.
There will also be a huge amount of pressure to perform at Chelsea, with the misfiring Torres and ageing Drogba the only backup following the departure of Samuel Eto'o - although it won't be anything he wasn't used to while at Atletico.
The key stat though is his goal scoring record apart from last season. Costa scored a total of 43 goals for Atlectico Madrid in a four year spell with the club, however with 27 of them coming last term, he scored just 16 in the three preceding years - little more than 5 per season on average.
Ander Herrera
Atletico Bilbao ---> Manchester United, £30 million
You could argue that a player like Ander Herrera - dynamic, skilful, great on the ball - is exactly the sort of player Manchester United have needed for years, and United made an attempt to sign him 12 months ago.
He impressed on his debut - the 7-0 friendly win over LA Galaxy - however he has made less of an impact in the following 5 matches. It's also curious as to how none of the other major European clubs were linked with moves for the Spaniard, while he has never been capped with Spain beyond U23 level - although in fairness Spain have somewhat of an embarrassment of riches in the midfield department.
One problem United have had in recent years is a scarcity of goals coming from midfield - but is Herrera likely to solve this problem? In his three years at the San Mamés he scored just 7 goals - or 2.33 per season. It was for his passing and assists that Louis van Gaal signed off on him having been identified by previous manager David Moyes, but the Old Trafford faithful will be hoping for more of a return on that £30 million rather than just some clever interplay.
Jack Rodwell
Manchester City ---> Sunderland, £12.6 million
Having impressed for Everton during the 2011/12 Premier League season, Jack Rodwell signed for Manchester City for an initial fee of £12 million. Unfortunately for the young English midfielder, his career at the Etihad simply never got going, and he departs two years on having made just 16 appearances.
At 23 he's still young enough to resurrect his career at Sunderland, but it will take time to find the form that made him a regular in the Everton first team following such a long spell as a perennial substitute.
He won't have to fight off the same level of competition as he did at Man City, but high standards will still be expected of him after the north east club made him their third most expensive signing of all time.
Bojan Krkic
Barcelona ---> Stoke City, Undisclosed
If you listen carefully you can still hear the murmur of excitement emanating from the Potteries after the news broke that Stoke City were signing a former Barcelona wonderkid - Bojan Krkic.
A player who broke Lionel Messi's record of bwing the youngest Barcelona player to feature in La Liga (Bojan was 17 years and 19 days old when he made his debut against Osasuna), great things were expected of the young Spaniard, but after failing to build on his early promise in four years at the Nou Camp he was sold to Roma in 2011 who loaned him to AC Milan just 12 months later.
Although Barcelona triggered a £10.5 million buy-back clause in 2013, however this was immediately followed by a loan deal to Ajax in the same summer.
So what are Stoke getting in Bojan? FIFA 14 PS4 Coins A player with some tricks up his sleeve certainly, but also someone who hasn't had more than one season with a club since leaving Barcelona 3 years ago.