This is a very good looking, sober and clean poster. The problem is that this is a Will Ferell sports comedy. And those have been known to use successfully some much less sober posters.
Perhaps the humor in this movie is a little different than that of recent Ferell films. More subtle, possibly. In that case this poster might offer an accurate idea of what the movie is like. But I think people have come to expect a certain type of film from Ferell, and a poster that makes Semi-Pro seem much different from that kind of film might keep some of his fans away.