Transfers
| Date | From | To | Type |
|---|---|---|---|
| 09.01.2014 | AS Roma | — | € 8M |
| 16.07.2012 | — | AS Roma | € 3.8M |
| 31.08.2011 | Borussia Mönchengladbach | — | € 1.2M |
| 01.02.2011 | Borussia Mönchengladbach | Aston Villa | Loan |
| 31.08.2008 | Heerenveen | Borussia Mönchengladbach | € 2.5M |
| 01.01.2006 | — | Heerenveen | Free |