Protective Pitcher apparel

Agree with the thigh wrap (like those used for someone with pulled hamstring). We've had pitchers use them in the past. You can get them just about anywhere, and they have enough padding to do the job. No need to spring $50 on padded compression shorts.

Thigh slap at end of windmill

The slap of the glove on the left thigh as the pitching arm passes the right thigh (RH pitchers) may very well provide the hitter a clue to time the pitch.

However, in my opinion the benefits outweigh the negatives -- it just doesn't work that well for the batter -- several posts have videos of Cattanauch, Finch, and Yeuno (?) and all 3 bring their glove down to their thigh as they arrive at the ball release point.

When I'm working on a DD's delivery, it is extremely beneficial to the timing and coordination of each arm when the glove arm swings down to the stride thigh. As I mentioned in an earlier post, for younger pitchers, it really puts a stop to their tendency to close the body prematurely (before the ball hand passes the thigh). Young/inexperienced pitchers want to use their body to turn to the closed position (and thereby pulling the arm thru) to get their speed up. Using the glove arm as mentioned really helps to correct that problem.
Jim