Designated HitterSeptember 01, 2006
Parity and the National League
By David Pinto

I tend to think of parity in terms of the NFL. The definition I remember was that any team could beat any other team on a given Sunday. A more mathematical way of stating it would be all the teams have the same intrinsic winning percentage.

(Now, they don't have to be .500 clubs. The NL teams had a losing record to the AL in interleague play this year, indicating they all may be slightly less than .500 teams. But as long as they have about the same winning percentage, it works out the same. So for the purposes of this article, we'll assume parity exists when all teams have an intrinsic winning percentage of .500.)

What is an intrinsic winning percentage? It's the performance we'd expect from a team over a very large number of games. That is, if teams could play enough games to smooth out luck, the intrinsic winning percentage is the result we expect to see.

Now sometimes what looks like parity isn't. Here's a trivial example. Suppose all the teams in the NL played four games, and each team was 2-2. While that certainly looks like parity, it likely isn't. The binomial distribution tells us that after four games in a league in parity, we're most likely to get one team 4-0, four teams 3-1, six teams 2-2, four teams 1-3 and one team 0-4. Sixteen teams at 2-2 is a low probability event in a league in parity (.0004). So we can test for parity by looking at the distribution of wins in the league. So do we have a parity situation in the NL right now?

The average team in the NL has played about 132 games. If each team had the same intrinsic winning percentage, we'd expect there to be 13 teams with between 59 and 73 wins. In fact, there are 12 such teams in the NL. That's pretty close.

Another way of testing for parity is through simulations. There is such a simulator at Baseball Musings. Keep clicking enter, and you'll see very close wild card races, similar to what's going on now.

So we have two separate tests, each indicating that the National League is close to parity. Now, the Mets are really good and the Pirates and Cubs really bad, but otherwise the model holds. It's Pete Rozelle's dream.

Now, is this a good thing? On the pro side of the argument, lots of teams are in the race and that should keep more fans interested. People like to watch winners. If there's a high probability your team is going to lose on a regular basis, there's less of a chance of you going to the park (see Kansas City and Tampa Bay).

The downside is the quality of play, since there are no great teams. There's a certain artistry in watching a top flight club. I remember in the early 70's watching the Yankees play the Oakland A's. Oakland was a great team, winning three World Series in a row. The Yankees were getting better, but not the team they would become at the end of the decade. The A's came to town and dispatched New York easily. On defense, on offense, on the mound, the Athletics showed they were better. Teams could watch them play and learn how to go about playing baseball. They hit mistakes, they fielded cleanly, they made good pitches. They were winners and they knew it. Outside of the Mets this season, I don't think there's another National League team like that.

There's another kind of parity, one that we saw from the beginning of free agency to the end of the CBS TV contract and the strike. For lack of a better term, I'll call it revenue parity. The money from National TV was enough to even out the disparity in local revenue at that time. It was parity of opportunity vs. parity of outcome, if you will. All the teams had enough money to build a winner, and from 1978 to 1992 a different team won the World Series every year. The teams weren't evenly match, but the resources were.

This is the parity I prefer, where great teams are created, teams that others can strive to beat. Lousy teams come into being as well, teams from whose mistakes others can learn. It's tough to appreciate greatness without the corresponding failure. With revenue sharing and new National TV contracts, I hope we're getting there again.

David Pinto is the author of Baseball Musings. David worked for STATS, Inc. for eleven years, ten as the lead researcher for Baseball Tonight on ESPN. He's also hosted Baseball Tonight online at and is a former employee of Baseball Info Solutions.


See, I feel exactly the opposite. I love the parity in the NL. Teams like the Rockies actually looked like they had life this season. The Brewers broke out last season. The Reds held the wild card lead for a long time.

What can you expect from the AL? The Orioles are never going to win the division, the Royals have stockpiled prospects but the Devil Rays have shown it's a distance from stockpiling prospects to contending.

The NL has still had some consistently good teams, like the Braves and Cardinals, but these teams had setbacks, they weren't like the Red Sox and Yankees, whose fans could shoot off their mouths nonstop. I like the idea of nobody's fans being comfortable enough to be that obnoxious.

APiNG, I understand your comment about more competition, but did you sit through the recent Mets Rockies series? It was not an model of good baseball.

"I tend to think of parity in terms of the NFL."

Which is funny, because I have always thought of parity, at least on a single-season basis, in terms of MLB. There's always an NFL team that breaks away and goes 14-2 or thereabouts. The baseball equivelant would be finishing with about 140 wins! That's not parity, that's downright impossible. Even the best team every year loses a few games to the worst. It's basically just luck and natural variations that create this micro-parity, but overall, NFL games are much more predictable.

Yeah, by your definition, "The definition I remember was that any team could beat any other team on a given Sunday," MLB has far more parity than the NFL. If you're talking about one game, you can say one MLB team is favored over the other, but you can't say it's a lock. Heck, bad teams sometimes sweep good teams in three-game series. In football, if a bad team beats a good team once, it's a miracle.

The problem with many such discussions is that people take too short a view. The Yankees have dominated the AL East for about 10 years with Boston not at the top quite as long. Typically, such situations go in cycles-the Braves until this year, the Indians in the 90s, the As in the 2000s, the Cards and Mets for a while in the 80s et al. Such has been the case since the beginning of the game. Saying that the Orioles or Rays will never compete overlooks the game's history. There was a time when clearly the Phillies would never compete-a very long time. Same with the Cubs, Pirates, As, Red Sox, Braves, Indians. Since the 1970s, such long stretches of incompetence are rarer. And while the past 10 years have seen NY at the top, the previous 14 saw them struggle. This cycle will end also.

If parity means that a team as poorly run as the Orioles get rewarded with a post-season appearance, I'm agin' it. The Orioles will never win the division for a very good reason. They stink. The owner stinks. The GM stinks. The manager stinks. The player development system stinks. The scouts stink. They don't deserve to win until they fix the problems.

I'd MUCH rather root for a team that did the right things and just missed out on the crown, than a team that won one because the system was rigged so that random luck determined the outcome.

Thanks to GotowarMissAgnes for pointing out that what you see on the field is the product of everybody from the owner to the scouts. The great teams have great organizations behind them, and while there are cycles, for those organizations the teams range from great to merely good.

I'm surprised that nobody has argued that what passes for parity is just mediocrity. For the National League it may be neither. The NL in the last dozen years has added three new franchises and took on the then-dreadful Brewers, while the AL traded the Brewers for a presence in Florida.

The National League isn't weak, it's diluted, especially the pitching, but there aren't enough quality position players to go around either. It'll take awhile for the better organizations like the Dodgers and Cardinals to work their way up to dominance.