I belong to 3 leagues and have seen teams dominate for a long time. You do NOT have to Win the league to dominate in it. For example, a division I am in in one of my leagues one team went to the playoffs 8 out of 9 seasons and won 2 titles while getting there 3 times. Another team in the same league same division went to the playoffs 6 of 9 times and won 3 titles in 5 tries. Are these teams dominate? YES! Do they win the division every year? NO! But in this case, either team was playing for the title in 8 of the 9 seasons.

Now in another league I am in, we have had the same winner for the league for the past 4 seasons and that team has won that division 5 times out of 5 tries in 8 seasons.