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Why You Shouldn’t Overreact To The Diamondbacks Offensive Slump

Sometimes, these things happen.

Arizona Diamondbacks  v New York Mets Photo by Al Bello/Getty Images

It’s been a rough 3 weeks. From May 10th through May 28th, the Diamondbacks have gone 3-14. In those 17 games, they have scored a total of 43 runs, 19 of which game in two games (7 last Friday against the A’s and 12 last night against the Reds). Outside of those two games, they scored 24 runs in 15 games, for a paltry 1.6 runs/game. That’s bad.

As a result of this 17 game slide, the fan base has been going nuts. We’ve seen our post-season projections drop to as low as 17.5% on some sites. People have already brought up the ideas of selling at the deadline, how Goldschmidt’s career is over, yadda-yadda.

Essentially, these are all emotional (over)reactions to a negative event (or series of events). This is especially heightened by the fact that fans, by their due nature of being fans, tend to live game-by-game even though that is almost entirely meaningless in baseball. There is no such thing as a “must-win” series in April, May, or really any month in baseball (more on this later) but fans like to treat every game and every series as such.

But the reality is... it’s likely that we’ll be just fine.

Our Record and Run Differential

In the midst of all this slumping, there is something that has been overlooked by many fans... the fact that we’re still one game over .500 with a +11 run differential. Over the course of this 17 game slump, we only gave up 62 runs, which comes out to 3.65 runs/game, which is actually really good.

Fans tend to remember two things more than anything:

  1. What has happened most recently (recency bias)
  2. Things that are more negative (negativity bias)

Both of these are very well-studied and understood facets of human psychology. Being a sports fan plays directly into these biases. And that’s the thing - these biases make us forget that we played like a really good team before this slump.

The fact that we’re still above .500 and have a positive run differential shows that in the long run, we’re still likely to be a .500 team or better. Run differential is far more predictive of future results than anything our offense and/or pitching are showing right now.

This slump does absolutely hurt our playoff chances so the effects of this are very real. However, this does not mean our offense is doomed for the rest of the season.

The Slump Wasn’t Really a Result of Regression

In times of doing well, we always have those fans that are calling for regression, negativity, or just overall doom-and-gloom going forward. Sometimes, these feelings are appropriate, especially if there is something that is highly regressible. In other times, regression gets blamed when the actual cause is just normal natural variation.

This is the thing that gets lost sometimes within the mixture of stats and fandom. Us saber guys are always telling you “regress to the mean” and “expect true talent level going forward”. And while both of these statements are generally true, they also come with a huge assumption: in the long run.

The reality is that baseball players are human and just like every single human on this planet, we have natural variation built in to everything we do (and this goes well beyond the scope of human nature: we see this is nature, in manufacturing, in physics, everywhere). What does this mean?

Sometimes we do better than expected. Sometimes we do worse than expected. Sometimes we perform in the middle of those two extremes. Sometimes we get lucky (high BABIP), sometimes we get unlucky (low BABIP). Sometimes we’re in the middle.

In the context of baseball, these things all even out to a player’s “true talent level” in the long run (aka after a large enough sample; we’re talking thousands of PAs and IPs). But in the short run, we will often only see one side of this circle of variation and this is what we’ll base our assumptions off us (e.g. recency bias).

But this is why sample sizes DO matter. It’s stupid to make any sort of reasonable assumption based off a 17 game sample. We have a long, established track record for nearly every single hitter on our roster; why would we suddenly believe they all suck at the same time and it’s going to carry on like this? The reality is that they aren’t all suddenly bad but our fan emotions make us believe that this is what is happening.

(note: this is also why platoon splits suck, have sucked, and will always suck. Just don’t.)

So let’s look at the actual offense during this slide and compare it to projections. I’ll warn you now: it’s not pretty.


Grouping Avg. OBP SLG ISO wOBA
Grouping Avg. OBP SLG ISO wOBA
May 10th - 28th 0.179 0.244 0.288 0.109 0.237
Projections 0.250 0.326 0.414 0.164 0.317

This isn’t regression. This is flat-out underproduction to a significant extent. We have a 44 wRC+ during this time frame. The second-worst team is the Minnesota Twins at 70. That’s our big our difference is.

But sometimes, shit happens and everyone decides to suck at the same time. Usually teams will have some players hot and some players cold at any one time; we just happened to have everyone cold at once. THIS STUFF HAPPENS. But I think there are two telling signs:

BABIP: .233

xwOBA: .295

Essentially, this slump comes down to poor results on our batted balls. This doesn’t excuse us entirely - our .295 xwOBA is well below our .317 projected wOBA, but it shows that we still had some pretty unfortunate things happen to us as well. A .295 wOBA is about an 85 wRC+ in neutral stadiums - not great, but a significant step above the 44 we’ve posted in the slump. And with out good our pitching performed, you have to think we would have been closer to .500. Alas, the joys of baseball.

Relax, Don’t Worry (About the Team as a Whole)

Our offense is going to come back. We have some good offensive talent on our team, even if it’s been injured quite a bit (Lamb, Souza Jr., Pollock). Our .317 pre-season wOBA projection is good for a roughly league-average offense in a neutral stadium (so about ~95 wRC+ for AZ). This is roughly what we should expect for our offense going forward, adjusted a bit for injuries and player changes. But this 44 wRC+ nonsense isn’t going to last. And last night’s game might be an indicator of that changing.

It’s okay to still worry. Our postseason odds have dropped dramatically thanks to this slump. This slump does showcase that we have some pretty glaring holes on our offense. Also, while the team as a whole should perform just fine, this does exclude us from looking at individual hitters that might be showing cause for concern (Goldy, Marte, Avila, etc.).

So don’t worry about our offense as a whole. It’s going to be decent. Instead of calling the entire team to be doomed, look for opportunities to fix individual positions in the long run.