2015-16 La Liga Preview: 5 worst transfers so far

The summer window is a busy time for managers and club directors, and this year's edition was no different in Spain as players were bought and sold across the league.

Not every transfer ends up working out, and not every signing is worth the (often exorbitant) cash. With that in mind, here are the worst transfers in La Liga (so far) ahead of the 2015-16 season.

5. Alvaro Negredo - Manchester City to Valencia

Reported £23.8-million transfer fee (Read more)

Valencia pulled off one of the biggest transfers of the summer window, completing a big-money signing of Spanish striker Alvaro Negredo from Manchester City.

The problem is, Valencia didn't actually want him.

Negredo's loan deal with Valencia from Manchester City included an obligatory buy clause, and Valencia was forced to purchase the Spanish striker for a whopping £23.8 million. Valencia is now looking to offload Negredo after this bit of business went sour.

4. Iker Casillas - Real Madrid to FC Porto

Undisclosed transfer fee (Read more)

It doesn't matter what sort of personal drama Real Madrid's executives had with Spanish captain Iker Casillas - you simply don't treat a club icon the way Real Madrid did, giving him a quick thank you and goodbye before shipping him off to FC Porto.

For the Portuguese outfit, capturing Casillas is an incredible coup. But for Real Madrid fans, losing their leader, the man they called "Saint Iker," with nothing more than a whimper, a forced smile, and a parade of trophies won't sit well.

3. Arda Turan - Atletico Madrid to Barcelona

€34-million transfer (Read more)

There's a reason Barcelona winger Pedro reportedly wants out at the club; with Luis Suarez, Neymar, and Lionel Messi as your competition up top, where will he find playing time?

That's the exact question Turkish winger Arda Turan now faces after swapping Atletico Madrid for Barcelona. When is he going to play? His €34-million move - a massive transfer fee for a part-time player - sees him plant his bottom firmly on the Barcelona bench. If Pedro doesn't depart the club, those minutes will be even harder to come by, too.

Oh, there's also the minor issue of not being able to actually play for the team until January as a result of the club's transfer ban.

2. Gael Kakuta - Chelsea to Sevilla

Undisclosed transfer fee (Read more)

Gael Kakuta is past the point in his young career where pundits and managers can look at him and say he shows potential. At 24 years old, Kakuta is now expected to perform. Unfortunately, over the course of the last six seasons, he's done the exact opposite, which somehow prompted Sevilla to drop cash on the Chelsea man for a permanent transfer.

Kakuta doesn't exactly have any links in Seville, as he didn't spend one of his six loans at the club. It's a confusing move, partly because it's a permanent transfer - could the club not loan him in? Why risk the cash? Curious, indeed.

1. Filipe Luis - Chelsea to Atletico Madrid

Reported £11-million transfer fee (Read more)

Filipe Luis is back in the red-and-white stripes of Atletico Madrid, but his journey back to the Vicente Calderon was a bit of a head-scratcher. He moved to Chelsea last year to the tune of £15.8 million and was bought back this summer for £11. million.

Like buying a used car, Filipe Luis is a diminished product, but even at a £4-million profit, the move seems awfully expensive for Madrid. Chelsea's financial department will be quite pleased to recoup so much of Filipe Luis' transfer fee while Atletico Madrid will be wondering if it could've struck a better bargain for the aging full-back, now 29 years old.