Competitive Balance III: Upward and Downward Mobility

I left off in my competitive balance series with a discussion of team mobility. By one measure, teams have proven far more upwardly/downwardly mobile in the NFL than they have in the other three major leagues. The graph below indicates the average annual change in team win percentage for the four major leagues:

However, this graph gives far too much credit for teams that move up and down within the middle ranks of the leagues without making too much progress from the absolute depths to the absolute heights, or vice versa. Meanwhile, Tom Tango over at Inside the Book presented a test that avoids that problem:

One sign of a competitive league is when a team that ends the season in the bottom third one year can manage to end up in the top third within the next three years… Basically, you have about one chance in three of having at least one competitive season in the next three seasons, if you finished in the bottom third of the league in standings. Let’s call this “The Rule of 3”… My question: who wants to try this exercise for NFL, NHL, and NBA? 

Well, since I already had the data I volunteered to answer that question. The following table is based on teams from 2000-2007, measuring their upward and downward mobility three years hence.

	Upward %	Downward	Total
MLB	36	31	67
NFL	47	44	91
NBA	44	41	85
NHL	48	43	91

As you can see, baseball is the laggard again. However, unlike the graph above, these data show that the NHL is just as mobile as the NFL, and the NBA isn't far behind. If I were tempted to jump to conclusions, I would suggest that this says a lot about the importance of playoff attainability and salary floors regarding competitive balance.