I had the regular pocket radar but traded it in for the ball coach model. The ball coach model is 1000x better. The old PR was terrible for baseball.
The stalker is a good bit better for getting velo at games or places where you're not close to the action (300' range vs 90', I think). The stalker also gives you piece of mind that you're getting accurate results, since it's the gold standard. But all that being said, the Ball Coach Pocket Radar is plenty accurate, convenient and good enough for most uses.