Roger’s comments are spot-on, as usual.
Your son’s glove side looks ‘soft’. Many kids can pitch okay at the 9 - 10 yo level with that flaw; however, they will not fare as well by the time they are 11 - 12 years old. After about 13 yo, you basically won’t find any successful pitchers who let their glove flop loosely to the side before release of the baseball. “Pulling the glove into the body” is also not the answer…the majority of elite pitchers swivel their glove into place somewhere over the stride foot during launch of the baseball, and they bring their chest forward to meet the glove as they release the ball. This helps to direct all of the the pitcher’s momentum forward–toward the target, where it should be.
It takes lots of correct repetitions to replace a bad old habit with a new good habit. Especially with the glove-side mechanics, kids who have ingrained a flaw for years will feel very uncomfortable when (if) they are coached to do the right thing.
The earlier you start your son doing the right thing with his glove-side, the easier it will be for him. If you procrastinate, or simply think “he will probably grow out of it”, or if you think “a Little League coach will teach him the right way” then it may become difficult for your son to keep pitching effectively within a few years.
I agree that your son and Vlad4040’s son both look pretty good compared to typical 9 yo pitchers but, unfortunately, that is not really saying too much of value–most 9 yo pitchers are not very good and can’t throw strikes consistently from 46’ away. If your son does throw strikes pretty consistently, it’s going to make him look good among his 9 yo peers. Hopefully, you can enjoy his 9 yo successes without becoming complacent about working toward better things to come…
See also: My comments for vlad4040 in the “My 9 yo son Take 2” thread.