My guess is teams who know the regular season doesn't matter because they are in get better ratings than teams who know it doesn't matter because they aren't.
I don't disagree with you in general, that there needs to be a rational balance between rewarding play and entertainment, I just think we are a little ways apart on where it falls. I didn't like the move from 4 to 5, but it grew on me because it incentiveized winning your division in a format where schedules were unbalanced. The 5 to 6 move does nothing for me. Inherently a baseball playoff format is going to suffer because it's a sport won on the margins, and you can't capture that it a 7 game series.
Flip side, football, particularly college football, is the opposite. That's why I support the 12 team, 10-2 model, with first round and quarterfinals played on campus. It gives meaning to all of the conference races, but doesn't actually prevent the best team from winning. UL Lafayette can storm the field when they win the Sun Belt, I'll actually watch the game, and then they'll go get blasted 56-10 in a road game at the SEC runner up a week later. We'll get to the same(ish) 4 teams, but on a more entertaining path.
I actually think the better solution for pro sports is to do a slanted win requirement. Do a 16 team playoff, so fans have a reason to stay invested, but while the 5, 6, 7 and 8 seeds have to win 4 games, the 1 seed just has to win once, the 2 seed twice, the 3 seed thrice, and the 4-5 is a true best of seven.
