5. Alex Song
Barcelona midfielder Alex Song was signed in 2012 off the back of two fantastic seasons with Arsenal, proving his worth as far more than a defensive presence and consistently combining with Robin van Persie thanks to a surprise eye for a looping through ball.
Song simply hasn't been good enough to dislodge any member of arguably the best midfield on the continent though, while also failing to convince in a cover role in central defence.
The 26-year-old has made just 14 appearances in La Liga this term and with Barca facing a transfer ban could be stuck on the bench for some time to come.