No.
In that case maybe.
How could you possibly know that? Last season Santana posted declining numbers. He led the league in homers allowed, his ERA jumped up over half a run, his WHIP and walks went up, and his most comparable pitcher according to BBRef comparability scores is Tim Hudson (a guy who peaked at 28 and hasn't been the same since).
You have no idea how Hughes' career will play out; he was the #1 pitching prospect in baseball going into this season and many scouts have compared him to a young Roger Clemens. He would have thrown a dominating no-hitter this year if he didn't pull a hammy and he was dominant in his postseason appearance.
I'm not saying Santana isn't better than Hughes; I'm saying I'd rather keep Hughes when in all likelihood Santana will be available as a free agent next year. I'm not willing to give up big prospects to essentially sign a player to a huge free agent contract a year in advance.

