After his injury he came back in 2010 fighting for podiums and even won a race. He started the season winning the first race and got third twice before the crash. He ended up third behind Ped, despite his injury and he stayed in front of Stoner on a horrible Ducati.
Rossi joins Ducati and proves how horrible that bike is on bikes that have improved all around him. He's had one bad year on the Ducati and looks like he'll have another and people are calling him to leave. He's won 7 times in Moto GP and he is early 30's... he isn't in his 40s and still has a good few years left in him yet.
He still has the speed, he just cannot learn how to ride differently at his age like Stoner could adapt at the young age he joined Ducati. Plus Rossi cannot afford to crash again and push the bike and has the same complaints stoner did. Lets not forget Stoner kept crashing out because of the Ducati and never looked like winning the championship for years on it after 2007, when the bike was good.
Rossi beat Stoner in 2008, beat Lorenzo in 2009 and thanx to an Injury and a bike he hates, he has had two bad seasons so far. It's true a young Rossi would be doing better on this bike, however he has far but lost it.
I'd personally love to see Rossi, Lorenzo and Stoner all on the Honda, that would be a great battle.