Monday, August 14, 2006

How good was the WHA?

In 1985, Bill James’ famous minor-league study determined that the level of pitching in the majors was 18% higher than in AAA. That is, you’d have to discount minor-league hitter’s stats by 18% to predict what they would have done in the major leagues.

In “
League Equivalencies,” an article on, Gabriel Desjardins looks to do the same for hockey.

For instance, Desjardins found all players in the 1972-73 WHA (its inaugural season) who played in the NHL the following year. Those 39 players subsequently scored 46% as many points per game in the NHL as they had in the WHA, and so the “league quality” of the 1972-73 WHA was 0.46.

The WHA’s 0.46 was only slightly higher than the 0.43 for the minor-league AHL that year. “This is not surprising,” Desjardins writes, “since the WHA mined the AHL to fill out its teams.”

The WHA’s quality increased during its life – up to 0.76 the next year, and then irregularly to 0.89 in its final season of 1978-79. By contrast, the AHL stayed in the 0.50 range in the 70s, and is now at 0.45.

The Russian Elite League is the highest-quality non-NHL league at 0.91; the Czech league is second at 0.61, followed by Sweden (0.59) and Finland (0.54).

Desjardins argues, also, that the “real” quality is likely to be higher than the figures he presents, because players moving to the NHL normally get much less power play time than they did in the other leagues. That reduces their point scoring more than just their ability would suggest.

To which I would add: what about playing time? Wouldn’t it also be true that players good enough to be promoted will get less playing time in the NHL than they did in the minors? That would deflate their numbers even more. You’d think this would be a very large factor, at least as large as the power play issue. (On the other hand, you’d think that playing time in high-caliber leagues (like the Russian league) would be less of an issue, since the better the hockey, the more likely the NHL recruit is good enough to get substantial ice time.)

In baseball, of course, we have statistics broken down by plate appearance or outs made, so playing time is accounted for. In hockey, though, without playing time numbers, these results are lower-bound estimates and may be substantially off. But, on that basis, and taking the numbers for what they're worth, this is pretty valuable information.


At Friday, August 18, 2006 6:55:00 PM, Anonymous Gabriel Desjardins said...

you wrote: "To which I would add: what about playing time? Wouldn’t it also be true that players good enough to be promoted will get less playing time in the NHL than they did in the minors? That would deflate their numbers even more. You’d think this would be a very large factor, at least as large as the power play issue."

The study only looks at players who played 40+ games in both the NHL and the AHL in consecutive seasons. NHL teams need guys to play - you don't dress and sit on the bench for 40 games.

So everyone in the study likely got at least 8 or 9 minutes of even-strength ice time per game in the NHL. In the AHL, if they were first-liners, they might get 13 minutes. I'd guess the mean drop in even-strength ice-time is less than 20%.

But PP time for these guys goes from 5+ minutes per game to zero. And with such a high scoring rate on the PP relative to even-strength, losing PP time is a much more significant factor in reducing offensive production.

At Friday, August 18, 2006 10:07:00 PM, Blogger Phil Birnbaum said...

Hi, Gabriel,

What you say makes sense ... a five minute drop in PP time is more important than a five minute drop in even strength time. So "at least as large" was probably incorrect on my part.

Of course, the 20% drop is still significant. It would bring the AHL down from .45 to .36, say.

Thanks again for this study.


At Friday, August 18, 2006 10:33:00 PM, Blogger Phil Birnbaum said...

Oops, the adjustment for ice time goes the other way -- up, not down. So the 20% decrease in ice time would bring the AHL up from .45 to .56.

At Monday, May 11, 2009 3:24:00 PM, Blogger Robert Quinn said...

I just want to say that I been reading your blog since I discovered it a few weeks ago. I enjoy it very much and your logic is incredible.

I wanted to comment on the statement you quoted that major league pitching is 18% better in the MLB than the AAA. I do not think you can come to that conclusion simply by comparing the averages of players in the major leagues compared to their averages in AAA.

I have played baseball as a child and through college. I am sure that it is to the hitters advantage to see the same pitcher consistently. I understand that their are life long triple A players who do face each other often but many major leagues only spend a short time in AAA. Additionally major leaguers are given access to much more information about a specific pitcher before a game than a triple A players leaving them better prepared.
I can not prove this by statistics as I know a Sabermetric like you would expect in an argument. I just wanted to give my opinion as a life long baseball player.

So I believe that AAA is more than 18% below the major league level.

At Monday, May 11, 2009 9:23:00 PM, Blogger Phil Birnbaum said...

Hi, Robert,

Thanks for your comments!

The 18% actually applies only to hitters, and was based on a 1985 study by Bill James. As someone pointed out, there might be some selective sampling going on ... 18% was the drop for the players *who were actually called up*. Those, presumably, were the best-suited for major-league play, so maybe the overall number is less than 18%.

At Monday, May 11, 2009 9:35:00 PM, Blogger Robert Quinn said...

I understand that it only applied to the players who were actually called up. I'll give you an example of my argument

Joe Smith is in moving up through the minor league system. He spends 2 years in triple A where he hits 300. Presumably during this time period he saw pitchers for the first time, or at least only a few times.

Joe Smith goes to the majors and has a 10 year career where he bats 246 (18% lower). While he was in the major leagues he saw the same pictures consistently year in and year out. This was to Joe Smiths advantage as a hitter is likely to improve his average the more times he sees a pitcher.

Based on Bill James study Joe Smiths experience is evidence of the fact that Major league pitching is 18% better than triple A. However my argument is that Joe Smith had a greater advantage in the major leagues in seeing the same pitching more often. If say, Joe Smith spent 10 years in triple A with similar opponents I think his triple A average would be better than 300, and if he was in the major leagues for only two years his average would be below 246.

So I think in order to validate Bill James accurancy, one would need to evaluate only those major leaguers who spend a similar amount of time in Triple A and the Major Leagues

I hope I explained this better this time.

At Monday, May 11, 2009 9:40:00 PM, Blogger Phil Birnbaum said...

OK, got it. So you're thinking that when a batter and a pitcher see each other often, the batter will eventually get the better of the matchup.

You might ask Tom Tango, and the authors of "The Book," whether that actually happens -- they might have studied it. Go to , and there's a link to a page where you can ask questions.

I'd be curious to see if that's true.


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