His career nosedived with some howlers down at the Den. In fairness he seemed to be doing OK and even became the Millwall Player of the year once but then hit some really bad form, became a liability and was dropped and never really recovered. His positioning became very suspect as well as coordination and flapping. I'm guessing the harder he tried the worse he became.
It's possible that he may rebuild his confidence and now would be a good time to do it without crowds breathing down his neck and without pressure because lets face it the Play Offs are all but gone. We may as well see if there is something still there or if he is still as bad as the end of his time at Millwall. The constant changing of clubs since and his inability to get a regular start at any of them would indicate that he hasn't convinced several other Coaches and Managers.
Dimi didn't exactly impress when he signed but the rest became history so I guess no harm in giving him a try, if he is worse then it becomes an easy decision in the summer regarding the pair of them.