First Pitch: Can We Trust The Pythagorean Record?

Ed Giles had two updates on Twitter today that I thought were interesting in relation to the Pirates’ Pythagorean record. We see that record thrown around all the time as evidence that the Pirates aren’t as good as their current record. But how much stock can we put in the stat?

Like any other stat, this one has to be put in perspective. First, it serves a good purpose. It tells what the team has done, and provides a great idea of what the team will do going forward. Prior to their 4-1 win tonight, the Pirates had scored 239 runs, and gave up 249. That amounted to an expected 33-35 record. Thus, their 36-32 record was lucky. And that gap has been closed with their huge win against Minnesota on Thursday.

Also like any stat, sample sizes have to be considered. In one of the tweets by Ed Giles, he pointed out that the Pirates had a -8 run differential in April, -21 in May, and +19 in June. That’s +23 after tonight’s win. So what does this tell us? It says the Pirates were a little below even in April, horrible in May, and have been great in June.

What does all of this tell us going forward? Will we see the horrible May version? Will the strong June version continue? Will they be like the April version — bad, but not horrible?

That’s where the other tweet by Giles comes in. He pointed out the monthly run differentials last year, which amounted to +6 from April through July. But then in August the Pirates were -54 and in September they were -44.

I could point to that and say “you can’t trust the Pythagorean record alone” and I’d probably be right. But I’d probably need to explain why. Everyone saw the Pirates’ pitching staff for what it was last year. They were overdue for a regression, and it just so happened that they did a 180 in the second half. So even though the run differential was positive, they weren’t expected to maintain their pace.

So how does that relate to this year? The pitching is expected to regress some, but not nearly as much. This is still a strong staff, and the weak points (Kevin Correia, Brad Lincoln) can be addressed with internal options (and should be addressed by those options sooner, rather than later). The hitting has been bad. I don’t think it’s as bad as May, and I don’t think it’s as good as June.

The Pirates have a lot of streaky hitters and one pretty consistent hitter in Andrew McCutchen. I think we’ve seen a lot of extremes this year with that combination. At times all of the hitters have been cold, except McCutchen. Right now we’re seeing a lot of the hitters on hot streaks, leading to the huge offensive output. This won’t continue, but neither will the “everyone is cold at the same time” trend.

I think the Pirates can expect a few hitters to get hot, McCutchen to keep hitting, and the pitching to regress a bit, but still be a strong asset. Add a bat to that next month to help out the offense, and I don’t see why the Pirates can’t continue putting up a positive run differential. It won’t be anything like their June differential so far, but it could amount to something that would justify a decent record from here on out. And considering their easy schedule over the next month and a half, I don’t think it would come as a surprise if they had a positive run differential.

The run differential tells us that the Pirates shouldn’t be sitting here with a winning record, and probably won’t continue winning if they play the way they have to date. But that’s the key. There’s no guarantee that they will continue playing the way they have, just like there was no guarantee last year after finishing with a positive run differential after the first four months. An easy schedule, adding a bat, and getting a few hitters hot at the right times could easily give this team a positive run differential, and maybe a Pythagorean record that justifies their actual record.

Links and Notes

**The Pirates won 4-1. Kristy Robinson’s notebook looks at A.J. Burnett finding the joy in baseball again.

**Prospect Watch: Strong starts from Justin Wilson and Clay Holmes, plus Quincy Latimore’s power surge continues.

**Prospect Notebook: Recapping the pro debut from Holmes, and other State College notes.

**Pedro Alvarez is seeking a consistent hot bat for the Pirates.

**As the trade deadline approaches, the Pirates are looking to improve all areas.

**Randy Linville had a good article on the Pythagorean record, talking about how the Pirates need to steal ten wins.

**Pat Lackey wants to believe in the 2012 Pirates.

Tim started Pirates Prospects in 2009 from his home in Virginia, which was 40 minutes from where Pedro Alvarez made his pro debut in Lynchburg. That year, the Lynchburg Hillcats won the Carolina League championship, and Pirates Prospects was born from Tim's reporting along the way. The site has grown over the years to include many more writers, and Tim has gone on to become a credentialed MLB reporter, producing Pirates Prospects each year, and will publish his 11th Prospect Guide this offseason. He has also served as the Pittsburgh Pirates correspondent for Baseball America since 2019. Behind the scenes, Tim is an avid music lover, and most of the money he gets paid to run this site goes to vinyl records.

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Craig Biddle

I posted about this last night, but here goes again.

Pirates have played 28 1-run games; they are 17-11 with a +6 run differential. Obviously, Pythagorean record has no merit when considering 1-run games; your W-L is exactly the same as R – RA.

Pirates have played 15 games whose final margin was 5 or more runs. They are 6-9 in these games, for a .400 W-L, and their Pythagorean expectation is a .391 W-L percentage, so they are very close to on the money here.

In their remaining 27 games, those decided by 2-4 runs, they have scored 96 and allowed 93, while going 15-12. This gives them a Pythagorean expectation of a .516 W-L, or about 14 wins.

So, in fact, they are within 1 win of expectation. What they are, instead, is a team that has so far played a lot of close games, and won more than their share of them. It is usual for teams that win a lot of 1-run games to be considered to be lucky. But does this apply to the Pirates?

Teams built on the Pirates’ model (two excellent starters, a decent remainder of the rotation, an excellent bullpen, decent defense, and not much offense) tend to be good at winning close games. Buttressing this tendency is the Pirates’ 3-0 record in extra innings. When other teams get past their setup guy and their closer (and sometimes even before that) they tend to have relatively weak pitchers on the mound late in games. The Pirates’ offense, while hardly earth-shattering, has been greatly affected by the fact that there are an average of fewer than 6 runs scored in games played in PNC Park, and about 8 1/5 in Pirates’ road games.

The standard correction factor for this among numbers geeks gives all Pirates’ hitters about a 7% credit for batting average and slugging percentage. If you apply that to the Pirates’ team batting stats, they have a slash line of .247-.286-.399. And adding 14% to their runs totals, they have scored the equivalent of 277 runs against a league average of 292. This is still not a great offense, but it’s not nearly as anemic as is generally believed.

I think their biggest need is a corner OF that can be a top of the lineup guy, with a good on-base percentage. Cutch, Alvarez, Jones, McGehee, Barajas, and Barmes are all decent to excellent power guys, but they would benefit by a few extra AB’s (due to more success reaching base at the top of the lineup) and RBI opportunities. There adjusted Slg% is actually over the league average, but their adjusted OB% is still below average.

Richard Ya'Zhynka

Where can I find the park correction factors?

Richard Ya'Zhynka

Excellent post. I like your reasoning regarding the Pirates success in one-run games. Those games go a long way toward explaining the Pirates outpeforming their Pythag and the factors you have cited indicate that the one-run record may well be a matter of team construction rather than luck.

Richard Ya'Zhynka

I did some tinkering with Pythagorean numbers yesterday. For the Pirates to 53 -40 the rest of the way and end with 90 wins (about what it usually takes to make the playoffs), they would have to keep up their current pitching, 3.66 runs allowed per game before last night, and score 4.17 runs per game – exactly NL average. Of course, they would also have to match the Pythag projection.

Richard Ya'Zhynka

I did some tinkering with Pythagorean numbers yesterday. For the Pirates to 53 -40 the rest of the way and end with 90 wins (about what it usually takes to make the playoffs), they would have to keep up their current pitching, 3.66 runs allowed per game before last night, and score 4.17 runs per game – exactly NL average. Of course, they would also have to match the Pythag projection.

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