With Lannan, Livan, Marquis, and Zimmermann basically in the rotation we only have one spot open. Id let Maya, Detwiler, and Wang compete for that spot rather than give up something for Blanton.
The point of addressing pitching this off season is to get a front of the rotation guy. Not fill up the back end. Blanton is nothing more than a 4 on a good team. Something like Marquis and Lannan. Since we already have two of those, along with Livan, there is no point in adding another. Allowing one of the unknowns to prove themselves is better for the long haul, and provides much more upside for this season as well.