He was actually fine after his knee injury, the start of last season (and the end), plus early on this season he looked excellent. It's the muscle injuries that have set him back weeks at a time that have stolen all his momentum in terms of form and sharpness. And let's not forget every injury he's losing acceleration, which at his age is a nightmare.
I think he'll go at the end of the season, and with regular football he'll reach a good, but not world class, level once more.