Estimating League Quality - Part 1 (the concept)
First of all, let me apologize for the lack of material posted to the Hall of Merit BLOG. In the coming weeks, I’m confident this will no longer be a problem.
When we consider players who played over 100 years ago, it is vital to look at the quality of the leagues they played in. Using a method that is similar to what Clay Davenport has been doing for some time (for examples of this kind of work, see Clay’s recent postings on Baseball Prospectus concerning the quality of play in the Japanese Baseball Leagues), I attempted to estimate the quality of baseball in the “major” leagues of the 19th century.
I focused on hitting stats, since at this time there were only a handful of pitchers active at a given time in a given league.
My method assumes that a player’s overall batting skill does not change appreciably from one year to the next. This assumption is not true on an individual basis, but it starts to make sense when we are talking about a large group of players. The individual changes in skill should become less important as the size of the group increases.
In leagues that are stable, there isn’t a very high turnover in personnel from year to year. In the 19th century National League, in most years, about 70%-80% of the players returned to play regularly the following year. In cases where new leagues started up and players jumped, the percentage of holdovers was much much lower - and this makes comparison much more difficult.
I estimated the quality of each hitter?s batting by using a runs produced ratio [(R+RBI)/PA] and compared it to a league average performance. The reason I chose this, and not Runs Created or Linear Weights, is that I wasn’t going to adjust for park and I assumed that the batting order bias of the R anbd RBI stats was not going to be relevant for a large group of players either.
In the 19th century, where more advanced run estimation formulas are much less accurate than for “modern” baseball, I opted for the simplicity of using Runs Scored and RBI.
Because we are comparing each group of players to league average the result shouldn’t be far from 1.00 for a relatively stable league (where the majority of regulars return the next year). In practice, it’s unlikely to be exactly 1.00 of course.
If the newcomers to the league in a given year were better than typical newcomers, the performance of the holdovers would be worse than in a typicla league and this would be a sign that the league was getting stronger. On the other hand, if a lot of good players jumped to a rival league and their places were filled by less skilled batsmen, the holdovers would improve their performance relative to league average and this would be a sign that the league was weakening.
By comparing the overall performance of the SAME group of players from year to year and league to league, it should be possible to track the changes in the overall quality of play.
In the next part, I’ll apply these methods to a specific example.
This thread will now be included with the Hall of Merit links.
August 6, 2004
Posted: March 01, 2002 at 10:49 PM | 173 comment(s)
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