Drop Morales/Masterson for Lewis?

[VUCommodore]

14-team mixed league, head-to-head with daily roster changes. My hitting is set, but I don't have a droppable player there. Trying to shore up my pitching staff after trading away my 3rd starter (David Price) for Josh Hamilton -- needless to say I didn't see that trade coming, but had no chance but to take it.

Pitching categories: W, SV, K, ERA, WHIP, QS

SP: Lester, Hamels, Oswalt, Buchholz, Latos, Masterson
RP: Aardsma, Dotel, Rauch, Feliz, Morales

(1) Do I pick up Colby Lewis?
(2) If so, who do I drop? Masterson, Morales, or prehaps Mat Latos??
(3) Why?