Sunday, July 16, 2017

The Great Run Differential Debate

As the Braves polished off the Diamondbacks on Sunday afternoon, ESPN's Dan Szymborski took to twitter. Things quickly went nutty from there.
Ignoring the "So...yeah..." at the end, the tweet is accurate. With a run differential of -34, the Braves are reasonably close in run differential with the Mets (-40), White Sox (-36), Pirates (-25), and Angels (-25). These are all below-.500 squads with the White Sox over ten games under .500.

Szymborski would go on to argue the point as Braves fans confronted him. When fans would bring up losing Freddie Freeman for a significant amount of time and having Bartolo Colon struggle tremendously with the Braves and how these things affected run differential, Szymborski pointed out that you can't just take out the bad things. You also need to bring up the good things that have occurred that can not be counted on to be sustainable (he brings up Tyler Flowers having a .400 OBP and Freddie Freeman's adjusted OPS+ of 202).

Here's the thing - he's not wrong, but his approach is abysmal as he goes on to say that he "missed the BARVES crowd." Gee, thanks, Dan.

But back to his underlying point. Run differential can mean something. It's not the end-all of stats and can be sample-size driven. At the same time, it can tell us - as the season progresses - if a team is playing over or under what we should expect from them. The Expected Win-Loss Record, also called the Pythagorean expectation, is a nifty little tool for snapshot reasons. Most of the time, it proves fairly accurate and we see regression one way or the other.

There is a good deal of accuracy in run differential. It tells a story and it helps us predict the future.

Moving on, is there validity to the idea that, if you remove Colon's struggles and the beating the Astros gave the Braves a few weeks ago, the Braves are a better team? This is the other accurate point Szymborski attempts to make. The Braves are just as likely to improve without having to face the Astros or have Colon pitch every fifth day as they are to regress due to players beginning to fall back to their means (their catchers, Johan Camargo, and so on). Every team is dealing with similar issues - some more than others - and bringing them up as signs that the run differential is false may lose context.

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But here's the good news for Braves fans. The Braves are a team in flux. Of their opening day roster, four have been released while four others are on the Disabled List. A ninth player, Anthony Recker, is in the minors and a tenth player, Jace Peterson, will likely be demoted on Monday. In most of these cases, the Braves have improved when replacing members of their opening day roster. Johan Camargo is better than Adonis Garcia. Danny Santana is better than Emilio Bonifacio. Matt Adams is tremendously better than Chase d'Arnaud. The arms of Sean Newcomb, Luke Jackson, Jason Hursh, and Akeel Morris profile much better than the ones they replaced. The Braves are improving incrementally most of the time they choose a member of their minor league system over a player previously on the major league roster. That's something that run differential cannot speak to.

Consider this. The run differential at the end of May was -42. It's now down to -34. That's not a huge improvement, but it is an improvement. We can go an extra mile. Over 59 games, from May 12 to July 16, the Braves have a run differential of +1. Here's the math - 289 runs scored, 288 runs given up.

Is that cherry-picking? You betcha. May 12 was a win that put a halt to a six-game losing streak and also improved upon a season-worst nine games under .500. I didn't specifically look for a way to find an arbitrary point that would show the Braves with a positive run differential, but it ended up that way.

The Braves may not be a great team. Certainly, I've made that argument over this season. Defensively, they have significant issues and the pitching staff has been a season-long project. But they are improving and for fans of the Braves, that's exactly what you should be looking for with this rebuilding team. Are they ready for primetime (i.e. the playoffs)? I have my doubts, but are they the same team that only won 12 of their first 32 ballgames? Again, I have my doubts.

In the mean time, it's much too simple to chalk it all up to run differential and predict regression. This team is not the same one that opened up the season by losing 6-0 to the Mets. For Braves fans, that's a breath of fresh air.

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