If Estrada continues to pitch as well as he has, would you offer him a QA? It would be a big raise (about 10M), but I think it could be a good gamble; either he signs and you maybe have an overpay, but it's just for one year, or he declines and tries to find a long term deal, and you end up with a high draft pick to help restock the system.
I wouldn't mind seeing him back next year, as he's done a good job, but I wonder what he would get on the open market, and if he would be worth it? He seems to be a good candidate for a bad long term contract (ie. Bourne/Swisher, or any number of Twins signings the last couple of years).