Clearly ur being sarcastic.
Clichy has an age advantage. He's already a starter for Arsenal which implies that he has the potential. Will he develop as some expect him to, i don't know. So far i know that he was average, then had a solid season and now he's back to being average again.
As far as i know he may never repeat the last season and slowly but surely lose his place inthe team and become history.
Since i also don't rate Grosso too high, if i have to chose one of them to play for Juve, and having the age difference in mind, i won't know which one to choose.
But if we talk about pure quality and if i have to pick one of them only for CL and important matches, then picking Grosso is a no brainer.
