if you lose Jimenez your starters will be- Hamels, ESantana, Liriano, Lohse, Parra, Cahil.
your solid closers are Rodriguez and Qualls. Villanueva will be out once Hoffman returns. Motte is interesting. he has the potential and could still end up being the guy.
im not very high on Jimenez myself. i think hes going to end up with alot of K but also an ERA into the 4's with a WHIP maybe into the high 1.3's.
however since closers come and go so often during the season i think it might be better for you to not trade Jimenez for Bell.
Santana is allready an injury risk this season. Hamels after so many IP last season could be an injury risk this season. Liriano is coming back off recent injury. i think it might be beneficial for you to hang onto Jimenez.