The kid you're trading with seems a bit nutty.
Personally, I'd rather trade for one solid pitcher rather than for two iffy ones. But, you are getting a SS back and a new 3B... So, I think it falls down to risk and reward here. Dempster and Zambrano are both capable of putting together decent starts, although not with much reliability. Aybar is an okay SS, downgrade over Rollins. Chipper is okay, but iffy for the year on the whole, and losing Walden wouldn't be great.
So, I say no. If you want to upgrade, trade 2 for 2, and try to snag better players.
Good luck! Help on mine?