Don't do it. Markakis is getting better and contributes in 5 categories. Verlander is wildly inconsistant. I think having 6 batters and 2 pitchers is ok.
If Heyward were a little closer I may consider it, but as it stands he looks to be a few years away from contributing. Verlander is too inconsistent and the Tigers are a trainwreck.
You are getting two ? marks for a sure thing. Stick with Markakis. I would see if you could still land one of the two for maybe Hart or Atkins but don't do that deal.
"In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move."- Douglas Adams
I agree with what was said above. Verlander looked lost last season, and while I view Heyward as one of the top prospects in the game, he is still likely a few years away. I would stay put with Markakis.