If he’s teaching that semi circular arm path, that tends to be more unsuccessful. If you look at most (not all but a lot) major league pitchers, they have a delayed hold after hand brake ( to prevent from early cocking) then they pintch the arm back while flexing the arm while moving the arm up. For an example of this, look at someone like Aroldis Chapman, Sonny Gray or David Robertson to name a few. Also, changing arm path could lead to changing your timing which could decrease velocity. Unless your arm path is really bad, don’t focus on it and do t change it. Focus more on a dynamic lower half.