Fair points, and those are the concerns. But if it works, he's worth 5 WAR every year. If it only kinda works, he's still probably going to be worth 2.5 (Randy Wells 09-10 range). If you don't think he can even replicate Wells, then sure, leave him alone. I'm less worried about him replicating Wells than I am with him ending up broken given his history. It could work, but even if he gives you 150 IP and then gets hurt, WAR may say you gained something, but you've lost a valuable guy by taking an unnecessary risk.