For me, Criscito's case reflexes the change of the BoD's policy. When Juve came back from the Serie B, the BoD wanted to develop youngsters alongside a so-called "5-year plan". Then it failed, part of which was due to that these youngsters were not ready or good enough but a another huge part was because the BoD wanted, at the same time, the results. Players like Nocerino and Palldino were sent away, even if they were no worse than some players who played for Juve later on and they cost nothing. They were not capable to play as first choice but they could be subtitute. On the contrary, with the amount of the cash that they were sold, the BoD brought in playres like Poulsen and Co. On the other hand, Marchionni has been proven to be no better than Palladino.
So now the BoD is changing their policy, buying proven players, even if some of them are too old.
Criscito had a good season but obviously he is still not good enough to play as the first choice LB for the new Juve the BoD wants to build. Although his performances were no worse (actually better) than what Molinaro and De Ceglie did in Siena one/two years ago, it seems that the BoD doesn't want to risk anymore. That's why they wanted to send De Ceglie to another team, too (De Ceglie is unwilling to go though).
Criscito is just unlucky. When he was given an opportunity at Juve, he was not ready at all and played at the wrong position (the BoD was just too blind to see it. They should let him play in Serie A for one season and obeserve him better) and now that he is much maturer the BoD just changed their policy, not willing to give him even an opportunity (I don't believe that Criscito is unwilling to play for Juve if the BoD has shown faith in him. When Molinaro came to Juve, they sold Balzaretti. Now Criscito is coming back, they are buying Grosso or Dossena).