Welcome Back, Offense

Do you remember last offseason? Last offseason, it seemed like Major League Baseball had two primary goals. One, it wanted to make the game move faster. And two, it wanted to do something about the ongoing drop in run-scoring. They didn’t really have a plan in mind, but they said it was a thing they were going to monitor. Last September, runs scored per nine innings dropped below 4 for the first time this millennium. And last year, also for the first time this millennium, there was a month with a league-wide OPS below .700. Actually, there were three of those months, in just a four-month span. Offense was going down; everyone was aware. Baseball needs a certain minimum level of offense to survive.

There’s your setup. This year, to some extent, baseball has succeeded in trimming unnecessary delays. The game does go faster, even if it’ll never go fast. And then there’s the matter of run-scoring. Here’s one plot, of year-to-year R/9 averages:

Hey, look, a little rebound. Relative to last year, this year is up 0.21 runs per nine, getting back closer to 2012 levels. That’s interesting on its own. But this gets more interesting the closer you look.

That, right there, is a plot of R/9 over each individual year. But we don’t need to stay at the year level. This is what happens when you break things down on a month-to-month basis.

In August, around the league, teams averaged 4.50 runs per nine innings. I don’t know if that seems like a lot to you, but again, last September, offense dropped to 3.96. The significance of that 4.50 — it was the highest mark for the league in any month since May 2010. So, that gets your attention, but it’s only one month. Well, we’re through the majority of this current September. And in September, offense has increased even more, to 4.71 R/9. We haven’t been here since August 2009. One partial month added on to one full month doesn’t make this inarguable proof of an offensive comeback, but this is becoming some really compelling evidence.

Run-scoring, of course, does depend in part on sequencing. So let’s try to strip that away. Instead of plotting monthly R/9, here’s a plot of monthly OPS.

The pattern stays true. The OPS in August was .736, the highest since August 2011. The OPS in September is .749, the highest since August 2009. So this isn’t just a weird sequencing fluke. There really has been more offense, for at least a month and a half, and given how many games and plate appearances there are, that seems like a difficult thing to just happen totally randomly. It can happen randomly! But one hypothesis is always “random noise.” Doesn’t mean we can’t investigate other things.

Here’s a plot of monthly BABIP:

August came in at .302; September is running at .305. Those are indeed slightly elevated. But then, last July, we had a .304. It was bookended by a couple .297s. BABIP could be a little part of this. BABIP is a little part of this.

How about strikeouts and walks? Maybe there’s been something up with the zone? Here’s K% – BB%:

No, nothing there. It’s hung at or around 13%, increasing slowly over time. A few weeks ago, at the Hardball Times, Jon Roegele talked about the strike zone, and observed the elevated offense in August. But he found no evidence that anything had changed with the zone. He found no evidence that pitchers had meaningfully changed their behavior. The zone has stayed big. Umpires haven’t become more batter-friendly. Maybe in time they will, but then, they won’t have to if offense stays up.

Here is, presumably, the biggest explanation. The rate of home runs on contact:

In August, there was a league rate of 4.1%, the highest since August 2009. And now in September there’s a league rate of 4.4%, the highest since August 2004. Again, yes, I know, it’s a partial month, but let’s put some stuff together. In this season’s second half, which is nearly complete, the league rate of home runs on contact has been 4.1%. Since 2000, there have been 32 individual “season halves.” This half’s rate would rank third-highest, behind only the first half of 2000 and the second half of 2004. The first half’s rate this year, incidentally, ranks 24th. The seasons below it are fairly recent. In the second half, homers have taken off, and they’ve taken run-scoring with it. It’s not just your favorite team that’s scoring more runs lately. It’s most of the teams. Sorry if that’s discouraging?

What you’ll notice is that’s an explanation that needs an explanation. Offense, all of a sudden, is up. The strike zone hasn’t changed. A small amount of this is probably BABIP-related, but it’s mostly about the return of power. Why has there been a return of power? And if I’m going to be completely honest with you, I don’t know yet. As it happens, I’ll be exploring this deeper in the forthcoming Hardball Times Annual, but I don’t yet have answers. No one I’ve spoken to has easy answers. It’s a weird and potentially complicated thing, but it’s playing out on a league scale.

Maybe it’s not sustainable. Homers are notoriously fluky, and the difference between strikeouts and walks remains a factor. It’s too soon to say that offense is back. But offense has been back, for a couple of months. It’s been back at the levels it used to occupy. The expanding zone seems like a problem, but if this is what we have now, maybe it’s less in need of a change than we thought.