If you watch his training video with Calvin Johnson, tall receivers like Butler can be easier to cover in press coverage because with the contact allowed in the first 5 yards Butler is a bigger target. There are ways to mitigate that and Johnson was trying to teach Butler some of that, but being a huge receiver in the NFL isn't the big time advantage some of us Cyclones fans have talked ourselves into.
It's not a huge advantage... But the way they are acting now it's some kind of huge DISADVANTAGE.