Re: Tony Cingrani - the next Zach Stewart or the next Cliff Lee?
I would hold unless you are just blown away by an offer. Odds are that at some point this season you will need him in your big league rotation.
You may have to make a different decision in June though if all 5 of the rotation guys are humming along, Ludwick is still a long ways away and LF ends up being a big problem.
The one thing I wouldn't do is trade him for a rental or expensive guy. If I could move him for another big league ready prospect at a need position, I might consider it.