The two tee drill is an old one. It goes back to the way hitting was taught very commonly 10 or more years ago, and fairly commonly even as much as five years ago. One of the "reasons" you'll hear for swinging down is to put more backspin on the ball so it carries farthers. It doesn't really make sense, but that advice was commonly accepted until recently.
Sounds like the coach offering this advice needs to update his video library -- to videos produced on DVD to start!
Sounds like the coach offering this advice needs to update his video library -- to videos produced on DVD to start!