Giants PQS Analysis: Expected ERA (qERA)

I am using the data from this previous post: Giants PQS: Updated to August 31st .

Analysis

Baseball HQ recently published additional research on their PQS creation here. In it, they provide a table showing the ERA of pitchers who fall into that particular bucket, based on a matrix of a pitcher's DOM% and DIS%. Apparently, I have been missing out on a whole facet of PQS that I haven't written on, which is how important DIS% is.

Not that I take total blame on that, it is just that they themselves never wrote much on how important DIS% is, other than obviously the lower it is, the better it is. But it is clearly very important. For DIS% of 10%, 20%, 30%, 40%+, there is a gradual uptick in ERA as the pitcher's DIS% rises. However, if you can get your DIS% to be under 10%, your ERA drops exponentially, particularly when your DOM% is at least the 40% mark that I have been noting appears to be the minimum level you need to be to be a good pitcher.

Based on the tables presented in the link above and using the DOM%/DIS% from the link at top, then extrapolating based on the actual DOM%/DIS% versus the table, assuming linear change from one cell to the next, to calculate the expected ERA based on the DOM%/DIS% pairing, I compiled the following table:

Name - DOM% - DIS% - qERA - Actual ERA (starter)
Cain - 48% - 28% - 4.71 - 4.32
Lowry - 33% - 19% - 4.64 - 3.75
Morris - 52% - 15% - 4.26 - 4.57
Schmidt - 59% - 4% - 3.40 - 3.37
Wright - 29% - 19% - 4.71 - 5.22
Hennessey - 11% - 11% - 4.58 - 4.13

Based on this, one can say that Cain, Lowry, and Hennessey have been very lucky thus far not to have a much higher ERA, and Morris and Wright have been victims of some bad luck, with Schmidt being pretty much on target. But because Hennessey was able to avoid a lot of disaster starts, his qERA is not much worse than Cain's despite Cain having a clearly superior DOM%. Same for Wright, just that extra 9% less DIS% made a huge difference between him and Cain too.

That's because when pitchers have a disaster start, it really is a disaster. As can be seen in the above link, the ERA for disaster starts was 11.19! Whereas dominant starts was 2.39. Obviously, there is self-selection there, but still, clearly, when a pitcher has a disaster start, he really goes whole hog.

And clearly from the matrix, it shows that getting your DIS% under 20% is key (and exponentially so if you can get it under 10% when your DOM% is over 40%), as well as getting your DOM% over 40%. As the study noted, a DOM%/DIS% of 50%/20% on average had an ERA of 4.50, but that is basically the same ERA if your ratio is 30%/10% or even 0%/0%. The only way to get an ERA of under 4.00 is to have a DOM% of over 60% and DIS% under 20%, or have a DIS% under around 5% while still having a DOM% over 40% (actually a shade under but I don't feel like calculating it).

What does this all mean? It confirms some things and shows who's just having bad luck. Obviously, from above, Morris and Wright are having bad luck. Morris has been pitching better than fans think he has been, he has been pitching pretty well, in particular his 52% DOM%. And it confirms that Cain is close to being an elite pitcher, if only he can reduce his DIS%. A DOM% of 48% is pretty good, getting his DIS% to low levels would push his ERA under 4.00.