...he is still maturing and thus has done things off the field at school that his hs coach probably views as signs of immaturity and the coach's response to these instances has not been to talk to him but rather issue stiff punishments on the field (sit him games, look at him with disgust and be very short with him in a no nonsense manner.
Sounds to me like the Coach is doing some parenting by disciplining an "arrogant teen with attitude". Sounds like Coach had/has higher expectations of your sons behavior. Sounds to me like Coach is silently inviting son to humble himself & straighten out the attitude. Sounds to me like Coach is telling this boy who is the boss on his TEAM.
As a senior in HS, your son is representing your family values, his HS, his ball team, his Coach, etc, etc. He's old enough to be choosing how he wants to be viewed (judged) by those who have the power/influence to help or hinder or...show apathy. He's in control of his own reputation & hopefully will STAND for what the Coach is wanting from him...as teammate, as a young adult, as a soon to be man.
While my kids were growing up, part of my job, as a parent was to teach "choice".. If son got into some situation at school or with friend/foe, think before you act/speak/react. If/when he committed a "wrong", address it immediately, & accept the consequences or do what was necessary to right the wrong.
Moral: You win or lose by the way you choose.