It's hard to look at Bojan's career and figure out exactly what went wrong. Having been brought through the ranks of Barcelona's famed youth academy, he has since taken a tour of some of Europe's most prestigious clubs while simultaneously failing to reach the heights that had been predicted for him.AS Roma, AC Milan and Ajax were all unable to get the best out of him, and he has since fallen out of the Stoke side to be sent out on loan to Bundesliga outfit Mainz. This was meant to fix him up for next season, but so far his time in Germany has been far from ideal.Having been brought to Stoke in an effort by manager Mark Hughes to change the perception of the club, he struggled to get back in the side following a fairly serious injury, and with his contract expiring, a loan spell in the German top flight was meant to put him back in the shop window.During the January transfer window he had his fair share of interest from around Europe with clubs in Spain joining Watford and Middlesbrough in attempts to sign him. Even Brendan Rodgers had hoped to take him to Celtic to join their unstoppable march to the Scottish Premier League title.However, he chose to link up with Jurgen Klopp's former side Mainz. Having not yet featured in the Bundesliga, he must have figured that this was the best opportunity to sample the delights of the league.And we can see why he chose them. Last season the club shocked pundits by finishing 6th in the table and were hoping to push on and maintain their position again this term.However, when the Spaniard arrived the club were lounging easily in mid-table, but since then their form has dropped off drastically and they are now looking over their shoulders at the relegation zone.Last weekend Mainz lost 1-0 to Freiburg, which was their fifth defeat on the bounce, and furthermore, the 26-year-old isn't getting games.During the loss to Freiburg he featured for just ten minutes towards then end, and was an unused substitute the week before in their clash with Ingolstadt.He admitted in an interview with the Stoke Sentinel that this isn't what he was expecting when he joined the club, saying: "I was not expecting this situation at all, but it is football. I do not think about anything other than scoring points and the next game."When you are in a situation like this, it is not pleasant for anyone - not the players, not the coach, not the club. But it is a situation where we have to transmit positive thoughts between us. We have to be united."Mainz will be unlikely to take him on a permanent deal at the end of the season, given what he is likely to be demanding in wages coupled with his contribution so far.Reports have circulated that he has been in talks with Spanish side Espanyol, though he took to Twitter to distance himself from the gossip, maintaining that he is focussing on finishing the season off before speaking with Stoke about his future.

In hindsight, a move to Celtic wouldn't have been the worst decision that he could have made, as this loan spell will likely go down in infamy alongside those undertaken by Federico Macheda when he joined Sampdoria and Adnan Januzaj at Borussia Dortmund (and Sunderland, for that matter).

It's quite a drop off for a player that looked destined to be the future of Barcelona when he first broke onto the scene. Luckily for him he's still young enough to salvage something of his career, but time is running out fast.