Can a Preacher Be So Ineffective That He Shouldn't Be a Pastor?

As a teacher of preaching in seminary, one of my biggest burdens is how can I help some of these guys not become pastors? So have you pulled a guy over and said, brother, this is not your path? No, not yet. But I have followed how he's doing to see whether or not he's going to go in that direction. Almost always, for whatever reason, there's a self-selecting thing happening by which he goes towards counseling or whatever. It's not comfortable to tell a guy that he's not cut out to be a pastor.