because when he does freak out in the pocket, it just leads to him taking off to run, which isn't always a bad result with his skillset. Meanwhile, when Snead freaked out in the pocket, it led to one of two things: 1) him curling up in the fetal position waiting to be hit, or 2) throwing the ball up for grabs usually in Shay Hodge's direction.
Pocket presence is something I don't believe can be taught. Masoli actually had pretty good pocket presence. He was a running QB, but he felt pressure well, and when he did flee the pocket he kept his eyes down field. He didn't just lower his head and run, and most importantly he was willing to take a hit. Eli had the best pocket presence I've seen from a QB at Ole Miss. Obviously he was just a good QB too, but his pocket presence was natural. He felt the rush well, and when it collapsed (as it often did for him), he did a good job getting outside the tackle box to throw it into the seats. Also, he wasn't afraid to stand in and take one under the chin if that's what it took for him to be able to get the ball away.
You have to have decent instincts at QB. That, or you have to play with a great OL and playmakers outside so that you don't have to worry about using your instincts. Snead's instincts were about like my wife's sense of direction. If he needed to go right, he'd go left. If he needed to hold onto the ball, he'd throw it.