To clear some space for the Favs or Hill extension... I know Hill's agent initially said no but it still might be there.
Also, 2nd rounders do have value, but when you have a million of them and can get more with small in season trades, Mack or Withey could be candidates, then it isn't that big of a deal to trade some of them. We don't have the roster spots for all of the picks coming in the next few years. I would have rather sent just one 2nd rounder, but if it's two and we have some other needs its fine. 2nd rounders are the grease to get deals done.
I'm actually more happy that we aren't making decisions based on sunk costs... one of the biggest issues in business and sports. We gave up value for Tibor, but if it isn't working admit it and move on. So many GMs compound problems by not allowing themselves to admit they were wrong.