I think you got it right. Drop Prado (you're not using him anyways w/ Polanco/Stewart/Gonzo/Beltre covering your 2B. 3B and IN spots and stash Elsbury for sure (He should be back soon so you'll have to drop someone to activate).
Only caveat to this is that with your league setup, Prado might have some trade value. IN that case, i would try to shop him first and then drop. Shop till you Drop! I just made that up and it sucks...but it applies here. No sense dropping someone you can get something for.
With the free spot left over, i'd go for Greg. Anytime you can start 4-5 RP's in a league i always load up with as many Closers as i can to maximize saves (unless holds are a stat). In my league, i only have two RP and one P so that people cant just pick up 5 Closers leaving not enough to go around the league.
Tough to leave those SP's out there in FA (What league has Bucholz, Pelfrey, Davis, Leake AND Lilly as FA's?!) but Greg could help you lock up a stat, where as those SP's may have a lesser effect on your staff.
Good luck and please help with mine:viewtopic.php?t=410770