Nusbaum probably has better judgement than me, but with Perales I see < 1 K an inning, nearly 5 BBs/9, a high HR rate, and FIP near 5. Maybe I'm too much of a defense independent pitching guy, but all of those are big steps back from pre-injury Perales. Anything positive in ERA is BABIP driven. Velocity is all the way back, also a positive, but he's not drawing chase.
As for Kent, I hope they hold off. The WC chase is kaput, so it's entirely a development thing. I think it will be hurt if he's added to the 40 man before the lockout, and there's no rush if he's working on recovering velo.