Miggy had a great season last year, until he got hurt. He was an RBI machine, and I think his wRC+ was over 120. If I remember correctly, his average with RISP was close to .500 with wRC+ over 200. Knowing he was healthy again, why would the Cubs trade him in the off season?
He's not as good this year, though he's healthy.
Either way, trading for a catcher doesn't make sense at all.