I don't know where y'all bowl, but for me, you cannot just kick people out of (or strongly suggest they leave) a league just because they don't average the same as everyone else. What if that was the only bowling center near them, or that was the only time they could bowl, or the wife is playing canasta, or it is Monday and the husband is watching Monday Night Football? Just because the bowler may not average high is a bad reason to exile them from a league with "180 average bowlers". I suppose monetarily speaking you don't mind losing the prize fund from that team. Or you always have teams dying to join your "you can only average 180" league.
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I am not a pro-bowler, but I do play one on BallReviews.com