Holy shit, there was a 1/2 grade dad that was already telling his kid to ignore the coach? I have never experienced that thankfully, but I have never had a ringer type player either that would even come close to warrant it.
The strangest thing i had was a dad came to practice and told me his son would not working with the team today. He would instead be running overheads around the court while we practiced because he messed up at school or something. I think we were 2nd grade. So we are practicing and this kid was running around the outside of the court with tears steaming out the entire time. Thankfully left after 30 minutes, but was back the back the next practice ready to work.
Yeah, there is always 'that one kid' who you wish was not in the rotation, but it can make for some cool moments. I had a 4th grade team where i had lost a good chunk of my team from last year so I agreed to merge with the remnants of a team that had folded but still had 3 kids that wanted to play together. Skill-wise i got a good big, a timid small and a kid that was legit special in some way. Load noises really bothered him and he had probably had a 1st grader's hand-eye coordination and could not run but sorta shuffled quickly.
League had sub rules where everyone played at least half the game, so had to get the line up just right to compensate because we played m2m D exclusively. Anyway, fast forward through to the end of 4th grade season and I seriously considered asking the other coach to let him just get a shot up in the last game, like a make-a-wish type deal, but held off. In the 5th grade season he had improved quite a bit (he did try hard in practice) and when he finally scored a bucket in a game the whole team went crazy and celebrated like we just won game 7 of the finals. it was really cool to see.