This is the deal with Hughes and maybe you do not want to see it because your a Yankee fan, he has only been successful in minior leagues. Yes he might has a great track record, but he is still a prospect and only that. My opinion is if my team can trade for MLB talent that can be had for prospects, then I would my team to do it. They can be called sure things, but the are not. Anything can hapen including some freakish injury.
Also you can compare WHIP for minior leagues to major and I laugh. To even write that is complete ignorant to Rivera's great season. Hughes did it in minor leagues, half the team is made up of bums. Rivera faces the best of the best, no bums there.
To put this in simple thems, if I could have Hughes or Johan to build a team with, I choose Johan everyday and twice on Sunday plain and simple. I'll go with the prove thing that's only 28, then risk it on a kid.