I would argue it goes both ways. The Canadian game is very different. Just look at Ricky Williams; his CFL career was an utter failure yet he is still going strong in the NFL. A recent CFL player who made the transition to the NFL is defending CFL defensive player of the year Cameron Wake, who not only made the Miami Dolphins this year but is having a great year so far. I have some friends who played in both leagues, mind you as long snappers, and they claim that in terms of athleticism both leagues are quite similar.