Having bowled in High School and College, let me add my take:
Since most High School Programs have a coach, they will make the majority of the decisions as to who is in/out, lineup, etc., a "Captain" is more of a honerary title. It should be voted on by the players anonymously. I want the Captain to be the person the team feel most comfortable with being the liason to the coach. If the team wants a change, I feel it's the Captain's job to take that to the coach and ask for it. And vice-a-versa, the Captain should be the person the team feels most comfortable with getting news from the coach, at times. I would also see the Captain(s) as some of the better performing bolwers, maybe not the top 1 (or 2) but near the top. People that can lead by example.
I was lucky enough to be a team captain during my High School career. I saw my job as being the guy to go out and perform for my teammates. But I also saw it as my job to help our coach, to be able to say to him "I think bowler X needs to make this move to score better" and see if he agrees and then giving that advice to bowler X. I also saw it as my job to help keep the team morale as high as possible. Cheering on my teammates and helping pick them up after a bad frame/open. I also, at times, sacrificed individual honors for team goals. For example, at the end of every season, there was a 2 day tournament that every high school could send 6 players to bowl. There were individual honors for singles and also team honors. I spent time going around and talking with our other 5 bowlers, pumpng them up, helping them with adjustments, cheering them on when needed, etc. I finished 3rd overall in Singles, but we won the Team portion and one of my teammates took the top overall Singles spot. I was more proud of that, then if I had won the Singles and our team didn't win. JMHO