Fielding in baseball (if not fielders, necessarily) is getting better all the time. Improvements in equipment, field conditions and, especially, defensive positioning, mean today’s players have a leg up on their predecessors. Indeed, today’s computer analysis of batter and pitcher tendencies is of a sophistication unimagined even as recently as a decade ago. And, to top it off, recent years have seen progressively fewer balls in play due to ever increasing numbers of strikeouts. The end result – fewer errors and fewer unearned runs.

Nevertheless, unearned runs haven’t disappeared entirely and some pitchers seem to allow more of them than others. As an example, these are the starting pitchers of 2012 (min. 150 IP) with the three highest ratios of unearned runs allowed to total runs allowed.

Surprised? I mean those are all pretty decent pitchers. Why would it be those guys? After the jump, I’ll explain why perhaps this shouldn’t be so surprising.

Here’s that same 2012 list expanded to the top 10 in unearned run ratio, those pitchers allowing more than 12% unearned runs.

Pretty decent set of pitchers. None with ERA+ below 100 or ERA above 4. And, with Verlander, Shields and CC, some of the top echelon pitchers in the game.

Maybe you’re saying this is one season. Doesn’t mean anything. Okay, fair enough. How about 50+ years. Here are the starting pitchers since 1961 with seasons (min. 162 IP) with unearned runs allowed above 15% of total runs allowed.

Wow! That’s quite a list of pitchers. Obviously tilted to the first part of the post-1961 period owing to the factors cited in the preamble. But, why such outstanding pitchers, as opposed to a more typical assortment of hurlers?

Here is my hypothesis. I welcome your feedback (not that I have to invite you, but go ahead and poke as many holes as you like). So, here goes.

1. This group will be allowing fewer runs (even a lot fewer runs) than “average” and “below average” pitchers in any era. Don’t think there should be much debate on this point.

2. The defense behind this group will play better than the defense behind an average or below average pitcher. Why? Fewer base runners, fewer pitches, fewer balls in play, balls in play not hit as hard, pitchers (probably) working faster – all these factors suggest less pressure on the defense and, ergo, less likelihood of committing errors that lead to unearned runs.

3. Factor #1 will be more pronounced than factor #2. That is, while the defense will play better behind this group, it’s not like they’re going to commit only half as many errors as they would behind a below average pitcher. However, a top rank pitcher may very well allow runs at a rate only half that of a below average pitcher, and perhaps 2/3 the rate of an average pitcher.

4. Taking the 3 points together, the reduced absolute number of unearned runs allowed that is expected for this group (point 1 and 2) will still be a larger proportion of their much lower total runs allowed (point 1 and 3), than would be the case for less skilled pitchers  (i.e. the great majority of major league pitchers).

So, there’s the hypothesis. It would be great if I could get stats on errors committed behind pitchers (point 2), but I don’t know where those figures might be. I expect the rest of the argument should be fairly self-evident. But, if I’m wrong, please let me know.

Finally, to illustrate my point about unearned runs declining at ever increasing rates, here are lists identifying the pitchers with the highest unearned run ratios by period. Notice the decline in unearned run ratio thresholds needed to generate lists of comparable size.

For 1901-1919, here are careers (min. 1000 IP) with unearned runs more than 33% (yes, 33%) of runs allowed.

For 1920-1949, let’s ratchet down that unearned run threshold to 18% of runs allowed.

For 1950-1992, we’re down to 15% unearned runs.

And, for 1993-2011, all the way down to 11% unearned runs allowed.