How good was the IBL really?

I'm not done yet with run estimation; I'm doing some work on the Linear Weights method. But I'd like to take a break to examine a different question, one which was on the minds of many fans last summer: What level of baseball did the IBL play?

It was clearly far from major-league standards, but did it reach minor league levels? If so, which level of the minors - AAA (the highest)? AA? Single-A? Rookie ball?

There are a few ways to go about answering the question. We can:

1. Look at people's subjective impressions.

2. Look at where the IBL players were recruited from.

3. Compare the performance of IBL players with other leagues they played in before or after the IBL.

4. Identify statistics which vary based on the level of play in a baseball league, and see how the IBL measured up.

I'd like to try all of these.


1. Subjective impressions

• With the quality of players we expect to attract, we are going to be able to provide a high-caliber level of play, probably most akin to Rookie League/Class A ball in the U.S.

-- The IBL, in advance of the season opening, expected to match the lowest levels of the minor leagues.


• It's a little higher level than I'm used to in college.

-- IBL pitcher Aryeh Rosenbaum describing his first two weeks of the season.


• The quality of play sometimes approached major league standards, while occasionally sinking to a high school level.

-- IBL pitcher Travis Zier writing after the season.


• The level of play was somewhere between college ball and AA minor league.

-- Rabbi Jason Miller, after attending a game.

There's something of a consensus: better than college ball, somewhere around the lowest ranks of the minor leagues.


2. Where the players came from

I don't have a complete breakdown, but it's clear that many of the players had only played college ball before coming to the IBL. Others had played in the lower ranks of the minor leagues, and some had played in independent leagues in the U.S., Europe or elsewhere. This is consistent with the assessment by method 1.


3. Comparing IBL player performance with their play in other leagues

I'm working on this, but it will take some time to gather and organize the data.


4. Compare the IBL with other leagues in terms of statistics which distinguish level of play

See, for example, the suggestion of "SABR Matt" at the beginning of this Baseball Fever posting:

Think about what kinds of events happen in the weakest of leagues and look for them in any league to measure its' quality relative to the strongest of leagues.

Bill James wrote down in one of his abstracts something like a dozen different kinds of things that happen a lot in bad baseball leagues and rarely in good ones. That list included Errors, "rare events" (like triple plays, baserunning outs, mistakes of aggression, base hits on pop-ups (why do you think we call those Texas Leaguers?) etc), passed balls, wild pitches, hit batsmen etc.

The problem here is that it's hard to find statistics for most of these "rare events". Baseball Reference, for example, a tremendous repository of baseball statistics, doesn't report HBPs, passed balls or wild pitches for the minor leagues. And neither do the websites of the leagues themselves.

About the only statistics I could find which fit this description are related to errors and stolen bases. It seems obvious that there should be more errors in weaker leagues, since the fielding isn't as good. For the same reason, presumably, there are more steals - the defense isn't as good at catching them.

(Note that you can't use batting-related data to distinguish level of play. A harder league has both better batters and better pitchers, so there's no relationship between, say, batting average and level of play.)

I collected data for the 2007 season of both leagues of the MLB and all the minor leagues listed on Baseball Reference and computed the following stats: Stolen bases per nine innings, Errors per nine innings, Unearned Run Average (which is like the ERA, but for unearned runs), and Defense Efficiency Ratio, a measure of defensive play which also takes errors into account.

Then I assigned each league a "level of play" rating: 1 for Rookie, 2 for A/A-, 3 for A+, 4 for AA, 5 for AAA and 6 for MLB. (I combined A and A- based on the preliminary results, which indicated they were too similar in level to distinguish between them.)

And now, the graphs. The horizontal axis represents the league level rating, and the vertical axis is the statistic in question. The IBL is marked by a large blue star.









The IBL seems to fall somewhere in the Rookie Ball spectrum, though obviously that's a rather broad spectrum. The level of play seems much more closely correlated with the league ranking for the post-rookie leagues than for rookie ball. I was actually surprised by how nicely linear the graph is for the most part.

Out of curiosity, I added to the graph two other independent leagues with no official ranking level, because IBL players have played there either before or after the IBL. Ryan Crotin, one of the IBL's leading hitters, played several seasons in Canada's IBL - the Intercounty Baseball League - where he was also a batting leader. And two pitchers from Israel's IBL, Rafael Bergstrom and Jason Benson, were signed by the indepedent Atlantic League after the season ended in Israel.

Judging by the graphs above, the Canadian IBL also ranks as a rookie league in level of play, not far from the Israeli IBL in level of difficulty. The Atlantic League, by contrast - labeled "ATL" on the graphs - ranks at about 3.5, somewhere between A+ and AA ball. This contrasts with descriptions categorizing the Atlantic League as "between AA and AAA", but I wouldn't place too much faith in the handful of statistics presented here. There's much more that goes into quality of play than errors and stolen bases, and anyway you could move the ATL point to 4.5 without getting too far off the regression line.

(My, those IBL players just kept stealing bases! Could that be a sign that I've got the level pegged too high? I guess I need data on college ball....)