As I mentioned in my prior fanpost about bye weeks, I was pretty unhappy with Topher Doll's post about expanding the NFL playoffs. In addition to my objection to his characterization of bye weeks as harmful, I thought that his research was insufficient to establish the point that expanding the playoffs wouldn't water them down.
Having finally done the additional research, I think I can conclusively say that expanding the playoffs WOULD water them down, quite substantially.
Numbers time! Here are the average number of wins for each playoff seed in each conference since 2002 (when the current 4-division winner playoff format was adopted), with ties counting as half a win. If you want to take a more detailed look at where these numbers are coming from, you can check out the spreadsheet here.
|5 & 6||10.45||9.86||10.16|
|7 & 8||8.86||8.55||8.7|
The very first thing that jumps out at me from this table is that the AFC was clearly the superior conference over the past decade (surprise, surprise).
But that aside, the important thing to note here is the noticeable drop in quality between the average playoff team (11.05 wins for the NFL as a whole) and the average new addition (8.7 wins for the NFL as a whole). Even if we want to look at how much worse 7 & 8 seeds would be than the worst current playoff teams, there's still a drop of about one win from the #4 seed (9.64; the #6 seed is actually slightly better at 9.73).
Furthermore, that actually understates the problem, because the distribution of team wins is not linear, but on a bell curve. Intuitively, this makes sense- 8 win seasons are far more common than 16 or 0 win seasons. As such, it should not be surprising that the gap between the the #1 and #2 seeds (1.21 wins) is quite a bit bigger than between the #5 and #6 seeds (0.86 wins), which is in turn bigger than the gap between the #7 and #8 seeds (0.77 wins).
Why does that matter? If every team in the NFL made the playoffs, the average number of wins for a playoff team would be exactly 8. The more teams we add to the playoffs, the less impact it has on the bottom line, because we're approaching that 8 win floor asymptotically. So the half-win drop in the overall average wins for playoff teams from a 6 team playoff (11.05 wins) to an 8 team playoff (10.47 wins) is actually much larger than it appears.
The problem with expanding the playoffs to 8 teams isn't that it would allow bad teams in. It's that it would allow mediocre teams in. When you look at the top couple of seeds, you're looking at teams far out on the edge of the curve. It's not easy to win 12+ games, so only a few teams do it, and you can be pretty confident these teams have earned their spot. The gap between the top playoff teams and the rest of the league is substantial.
But the hypothetical 7 & 8 seeds would mostly be coming out of the undifferentiated mass of teams that finish in the 8-9 win range every year. Looking back to my post about bye weeks, we can see that of the 31 10-win teams to make the playoffs since 2002, only 3 have made it past the divisional playoffs, and one of those three had a bye to get them past the wild card round. If we add four teams that average under 9 wins a season, can we really expect them to do anything significant? I have no doubt that a handful of them would win some games, but the idea that we'd be getting extra meaningful football games is dubious at best. And in the meantime, we'd be punishing the top seeds by forcing them to play another game, lowering our odds of seeing them play the genuinely meaningful football we want to see in the later rounds.
It is true, as Topher Doll noted, that only 3 of the 44 additional teams that would have made the playoffs since 2002 would have had fewer than 8 wins. But merely reaching 8 wins never struck me as worthwhile threshold. Let's look at how each seed does at crossing the 10-win threshold:
In light of this, does it really make sense to say that the playoffs wouldn't be watered down?