There ARE other things that would have to be considered in a Thomas acquisition beyond cap consequence and draft picks.
I agree that Thomas would improve the quality of the the Pats OT group...but the question would be by how much. How much better would the OL as a group be with Thomas? Then there is even the more important question of can Thomas play RT, and if he can't, can Solder make the switch after playing his entire career on the left side? For the casual fan it would seem like a no brainer, but in real like, as you know, it's not so easy.