Free Agency came about in 1975 and supposedly destroyed the competitive balance in MLB. We always hear about how the NFL does a much better job with league parity, but is that really true? Let's look at the championship teams since free agency came into being.
Baseball: 20 different WS championship teams
Football: 15 different SB championship teams
Red Sox: 2
Meanwhile the NFL has produced:
New York Giants:3
Think I'm cherrypicking? Want to change the argument to 1970, 1980. or 1990???
Want to also include teams that lost the WS or SB???? You'll still come up with similar results.
MLB has more parity than the NFL.