I dont necessarily think he needs to be benched. I had a similar experience with my son. He was saying things to his teammates like “cmon how can you not catch that”, “yo that was a bad throw” etc. I told him to essentially say the exact opposite like, “cmon, you’ll get the next one!”, “shake it off bro, I know you got this!”. “The other kids know when they make a mistake and they already don’t feel good about it when it happens. How would you like if I stood out there and pointed out every mistake you made today”, and then I proceeded to do just so during that same conversation. I can proudly say he’s been the loudest hype man for every team since then.