Game Score Plus Part 2: Some Context

Morning all. If you missed my introduction post last night, here is the link. In a nutshell, I explained that my calculations of Game Score “Advantage” failed me in that they didn’t hold up well between generations. A pitcher who started 40 games might regularly accumulate an Advantage score between 600 & 700, where today’s best pitchers often don’t even make it to 500 (Max Scherzer was #1 in 2016 with a 459).

Another major downfall of Advantage was the fact that nobody had any idea what it meant. Whenever I posted scores on my Cove Chatter Twitter page (which admittedly isn’t the best place for this kind of information), I was almost always prompted to provide an explanation of what those scores actually meant, how they were calculated, etc. Tip: if you’re going to come up with some cool, new metric to evaluate something, it better be easy for the general public to understand. As I learned, Game Score Advantage wasn’t.

If I was going to find the most dominant pitching seasons of all time (using Game Score), I needed a better way to compare pitchers across the decades.

That line of thinking led me to Game Score Plus, a simple metric that puts a pitcher’s Game Score Average in direct comparison with his peers that season, 100 being the league average.

Now for some context.

Any time a starting pitcher takes the mound, he automatically begins the game with a Game Score of 50. So, while the range of scores in any single game can vary pretty drastically, a pitcher’s average Game Score for the season generally falls somewhere within 10 points (+/-) of the base score 50. In a given season, the best pitchers’ averages are usually in the high 50’s/low 60’s (sometimes mid 60’s, and much more infrequently high 60’s/low 70’s); The worst averages among the league are generally in the low 40’s, while the majority of the group sits within 5 or so points of 50.

In 2016, for example, Scherzer won his Cy Young with an Avg GmSc of 63.5. Rick Porcello (a controversial pick all along to me) won his Cy with an Avg of 58.7, 15th best in the majors. Of pitchers who made 15 or more starts, Aaron Blair was dead last with a 39.5 GmSc Avg. The league average for all 145 of those pitchers was exactly 52 (down from 52.7 in 2015 & 53.5 in 2014). So, as I said, nearly all pitchers in a given season fall within 10 points +/- of the base score 50.

The questions that Game Score Plus attempts to answer is “just how good was Scherzer’s 63.5 average in 2016?” How poor of a season did Blair really have? Who were league average pitchers, according to Average Game Scores? What about Clayton Kershaw’s abbreviated 2016? Just how great was that, relative to great seasons throughout history?

Now the fun part. Game Score Plus can be easily calculated, so long as you have data for the entire league. I subscribe to Baseball-Reference’s Play Index, so that’s not an issue. First, a pitcher must have made at least 15 starts that season to qualify. We take his Average Game Score, divide it by the MLB Avg GmSc for all pitchers who made 15 starts, then multiply by 100. The 15 start qualifier is totally a personal choice. I didn’t want to include small sample sizes, whether good or bad, into my data. I wanted the data to be representative of the pitchers who made the majority of the starts in the league (those in it for the “long haul”).

The simple formula looks like this: GmSc+ = (SP Avg GmSc/MLB Avg GmSc)*100

The final result needs little clarification to understand. A 100 score is league average. Every point above or below 100 is one percent better or worse than the league average. Scherzer, for example, was 22% better than his peers in 2016, winning the Cy Young with a GmSc+ of 122. Aaron Blair’s rocky start to his career (15 starts) was exactly 24% below MLB average (76 GmSc+). Kershaw? His 21 starts at 70.3 Avg GmSc earned him a GmSc+ of 135, a whopping 35% better than the league. Had he been able to keep that pace for a full season, it would have been one of the 10 best performances in MLB history. Pretty crazy, huh?

I made a chart to help categorize Game Score+ marks, based on what the data back to 1913 shows me. Hopefully this helps clear up any confusion and aids us in analyzing different players and teams going forward.

Note: There have only been 30 or so seasons of GmSc+ 130 or higher since 1913. It is not listed on this chart, as 125 also qualifies as a season for the ages.

screen-shot-2017-02-26-at-8-33-39-am

Ok, I’m planning on writing more posts about Game Score Plus very soon, where we compare historical seasons, all-time greats, today’s pitchers, as well as our Los Gigantes rotation. But for now, how about looking at a prominent pitcher’s career through the new lens of GmSc+? I’ll leave his name off for now and let you see if you can figure out who he is. I don’t think it’ll be too difficult, as he’s someone we’re all pretty familiar with around here.

Note: ADV32 = Career Advantage adjusted per 32 starts

screen-shot-2017-02-26-at-9-57-02-am

Thanks for reading.

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