It will be very interesting to see. For sure his OBP is terrific but he's not that fast and seems to be declining (yes, he was hurt, but also on defense). Early this season he looked like he might be a legit .800 OPS player (he came close last year) but he failed big-time at that, so can he get back to being at least a .750-.760 OPS player like two years ago?
And I have no idea if he's a leader or not. Quiet guy. It was said they brought in Santana for that reason which also suggests Cesar wasn't in that role (which was previously filled by Galvis). Besides, if they move on from Hernandez, Franco and Herrera (still seems unlikely to me but not impossible) they won't have many Central or South American position players left. Even Machado's not one.
Last year Cesar was clearly worth more to the Phillies than he was to other teams in trade. That might still be the case this year but we won't know for sure until other pieces are in place. But at some point Cesar, Crawford and Kingery can't all be on the same team and the latter two players have a lot more years left in them, if less production at the moment.