IS4UA, I think people on this site will suggest the use of IR mechanics because this matches what the top pitchers in the game do. You don't have to believe what is said, simply look at the abundance of footage available of all types of college pitchers- all of them, to a one, come down the back side of the circle, elbow leading, ball up- whether they were specifically taught this type of mechanics or not, this is where they have ended up to be successful. As someone noted above, it is very likely that your DD's coach successful 18U+ pitchers are using IR mechanics despite what they are taught. If you want advice, mine would be to watch the footage of college pitchers and then decide for yourself what you think is best- but the other caveat (and this is from RLG)- you want to increase speed, focus on mechanics first