He's been around the longest, he's been injured, and has a history of not throwing strikes and going past the 5th inning. He isn't the same guy he was before his shoulder injury. I'm not sure he can get by at 90-93. His fastball command is nowhere near good enough.
Quite frankly, I still see room for growth with Giolito and Lopez but I don't see any with Rodon. There is some deterioration of stuff with Rodon after his injury, but that is to be expected.