This month, in a new series of statistical analyses, Bill James introduced some new ideas (to most of his readers, anyway) about defensive measurements. His posts at BillJames.com and the comments can't be read if you haven't subscribed to the site, but I'm repeating a few excerpts for non-commercial use only (I hope he won't mind that), and in any case, this post is written mainly for other subscribers to the site.

In the post that kicked off this controversy, Bill wrote:

"It is not a perfect and unassailable truth that Offense and Defense are perfectly balanced, that Scoring Runs is half the game and preventing them is half the game. It is not a perfect and unassailable truth, but it is a general and usable truth which can be validated in various ways. If offense and defense are equal then, on a "league" basis—understanding that the league is no longer a completely self-contained entity—but on a league basis, runs prevented are equal to runs scored. If there were 11,449 Runs SCORED by National League teams in 2019, there must also have been 11,449 Runs PREVENTED by National League teams—not perfectly, because the league winning percentage was not exactly .500, but we can adjust for that. The question is, who prevented how many of those 11,449 Runs that were Prevented by Defensive Performance?"

In the comments section to that article, nine different people, including myself stated either that they did not understand this argument or that they did not agree with it. Several others said they did agree with it, but the majority of respondents certainly did not.

Bill replied a few days later with a long rant (there's really no other word) in another post, informing all of us who had questioned this conclusion, in essence, that he had done everything he could to help us understand this argument, about which he evidently had no second thoughts, and that if we didn't get it, it was our problem. He also described any "argument" or "challenge to my work" as an"asshole question" to which he wasn't going to respond, and disclaimed any interest in any opposing arguments that we might make.

If Bill doesn't want to read this post of mine, that's his business. I am writing it for the other posters on his site whom he essentially ordered not to continue the discussion there. I think that the above statement is wrong, as is another follow-up statement he made in a later post that we will get to, and I want to explain why and solicit comments from other reasons on what they think.

Let's start with some simple logic. Let's look at the paragraph above. First I want to clarify something that could be clarified better, which I have run into myself: the reason league runs scored don't equal league runs allowed nowadays is interleague play. One league always scores more runs than the other in interleague play, and that unbalances each league's totals. That's a minor point.

But what about the statement that runs prevented must equal runs scored? That, it seems to me, is obviously wrong, for at least two reasons. The first is the simplest and most important. Runs allowed are not equal to runs prevented. Runs allowed are equal to RUNS NOT PREVENTED. That, to me, is so obvious that any further arguments are extra.

Yet there are further arguments. Bill also argues that what he is trying to do is to disaggregate runs prevented in the same way that the runs created formula disaggregates runs scored. It is true that every run scored is scored as a result of hits, walks, stolen bases, and a few other miscellaneous things, and no runs would be scored in the absence of those contributing factors. But runs prevented or runs saved is not comparable in that respect, particularly with respect to fielders One could argue that it is comparable for pitchers, since they could indeed prevent every single run scored by the opposition by striking everyone out, or by inducing easy chances in the field. But for fielders it isn't true. There are very large numbers of runs that no fielder could prevent, which are scored thanks to walks, to home runs, or--critically--to balls in play which no fielder could possibly turn into an out. The offense is a factor in every run scored. The defense (the fielders) is not a factor in every run allowed--if the offense was good enough, there wasn't a damn thing the defense could do about it. (Come to think to think of it--the same argument does in a sense apply to pitchers as fielders. While pitchers could in theory strike everyone out or pitch nothing but no-hitters, no one has ever been that good, any more than any three outfielders have ever been good enough to turn every ball hit beyond the infield into an out. But that's a side issue.)

Another fallacy in Bill's thinking emerges in a third, most recent post. Analyzing the 2019 Houston Astros, Bill calculates that based on the league averages of runs scored/allowed, they could have been expected to allow 840.32 runs. He then says:

"The 'zero point' for them is twice that number. If they had allowed twice that number of runs, that would be 1680.64 runs allowed. They actually allowed only 640 runs, or 1040.64 runs less than they theoretically might have allowed, had they had zero talent on their pitching staff and in their defensive play."

What Bill seems to be doing here is to find a baseline for calculating actual runs saved that is different from the average number of runs scored/allowed by every team in the league, a method which he repeatedly rejects. (And, for the record, a record which I, along with certain other sabermetricians, do use.) The selection of a "zero point" that is twice the park-adjusted league average, however, seems completely arbitrary. In fact, as one other commenter said on the first post, a team with zero defensive talent would never retire a batter and would allow an infinite number of runs. A team whose pitchers and fielders were half as good as an average team--that is, that walked twice as many men, struck out half as many, and allowed twice as many hits of all kinds--would, it seems to me (I haven't tried to do the whole calculation), allow twice as many runs as the average. That's a very bad team--I don't think there has ever been a major league team that bad--but it isn't an infinitely bad one, or a team with no talent at all.

I am not going to comment on the way Bill has chosen to handle this controversy. I have said many times in print that I understand a great many things thanks to him, that his work has given me many hours of pleasure, and that the baseball books I have written never would have been written without him. I will say, however, that from my own experience in my own career as an historian--which is quite comparable to his career as a sabermetrician, as you can see if you want at ALifeinHistory.com--I know that no level of skill, no amount of work, can exempt anyone, in any field, from criticism, particularly if one's work is genuinely original. And no truly intelligent person should ever be afraid to admit that they might have been wrong, as Bill has many times in the past.

Feel free to comment!