Dynasty league: Make some trades?

I'm working on getting my dynasty ready to roll for this season (and beyond, of course), and have already made a couple trades and am looking at a couple others. It's an 11 team roto that counts Runs, RBIs, HRs, SBs, BBs, OBP and AVG for batters and QS, WHIP, ERA, K, K/9, HLD, and SV for pitchers. I like my team for the very most part,but there are a couple things that aren't perfect and there are some trade options in the league right now.

Here's the roster...as you can see it's set up as a standard AL style roster:

C Yadier Molina

1B Adrian Gonzalez

2B Dustin Pedroia

3B Ryan Zimmerman

SS Starlin Castro

OF Jacoby Ellsbury, Jay Bruce, Justin Upton

UTIL Eric Hosmer

Bench Emilio Bonifacio, Daniel Murphy, Jason Heyward, J.P. Arencibia

SP: Yovani Gallardo, Jon Lester, Mat Latos, Brandon Beachy, Jordan Zimmermann

RP: Cory Luebke, Sergio Santos, Antonio Bastardo, Mark Melancon, Aroldis Chapman, Rafael Soriano, Francisco Rodriguez (MIL)

DL: Carl Crawford, Rubby De La Rosa, Brett Anderson, Jorge De La Rosa

I've also got Trevor Bauer, Jesus Montero, and many others who won't be relevant for a while in my minor league system.

Zack Greinke and Jonathan Papelbon were put on the trading block in my league a little while ago, and I've been considering making a move to try to acquire them. I'm considering offering Crawford, J. Zimmermann, and Soriano. I'm figuring that I since I traded for Hosmer last season to play UTIL, I can get rid of Crawford, especially since I traded for Heyward as my 4th OF. I'm perfectly content with my offense the way it is and I'm ecstatic that I've got useful guys with such great eligiblities on my bench. The only thing I'm not happy with is my closer situation and my SP5 slot. I'd feel a lot better about both with this deal, plus I don't have to worry about what to do with Crawford when he comes off the DL. My biggest concern is that adding Greinke creates a problem when Bauer gets called up, which I'm guessing will probably be this season or next season. Would you be concerned about that, or would you try to get a deal like this done and worry about an SP jam later? Assuming Bauer is used as a starter, I have 100 IP before he has to be called up, traded, or released.

What are your thoughts on this? Thanks for your help!