Bryce Harper was in a slump! You might not have noticed. Right around the middle of April, it seemed people decided Harper had somehow taken another step forward. And maybe he has, I don’t know, but if he has, he hasn’t done it since the middle of April. As a matter of fact — I’m writing this late Wednesday, and when I look at the leaderboards over the past seven days, Harper is tied for dead last in WAR. I don’t recommend you make a habit of looking at WAR over seven-day periods, but Harper is Harper, and last is last. There was a real and legitimate slump. Could be there still is.

Let me make it clear right now that I’m not concerned. Not about Harper, not at present. I thought he was great at the beginning of April, I thought he was great in the middle of April, and I think he’s great now at the beginning of May. Everyone is entitled to the occasional off-week. I just do think there’s something we could learn from examining how what’s happened has happened. Bryce Harper slumped! Why?

From April 26 through May 3, Harper went 3-for-28 with three singles and 13 strikeouts. Now, from April 27 through May 3, Harper went 2-for-26 with 13 strikeouts, which is worse, but I made a little error when I generated the following plots and I’m too lazy to go back and fix them. It doesn’t change the point. Here’s one of the reasons I’m not worried. Harper’s wOBA trends since the start of last season, over eight-game samples:

What just happened is a low, but last year between September 23 and October 1, Harper went 4-for-29 without a homer. Here’s the same kind of plot, but for Mike Trout, stretching back to 2012, when he became what he is:

You see the dips. Everybody gets dips. In 2014, in the middle of August, Trout went 4-for-32, with no homers and 12 strikeouts. Remember all those conversations? Now, here’s the plot for Barry Bonds‘ entire career:

Dips! In 2004, Bonds finished with a 233 wRC+. That was the second-best mark he ever posted, and that was the year of the .609 OBP. But over an eight-game stretch in May, Bonds went 1-for-20. That was within a 21-game span when Bonds went deep only once. In fairness, Bonds wasn’t striking out, but even the best hitter any of us living have ever seen had his ruts. It’s not that it’s unreasonable for worry about Harper to ever be justified. You’d just need more than a week of evidence. Probably at least a month and a half.

We can safely think of this as a blip. But even blips have their reasons for being. It’s hard to prove, but let’s assume Harper has had a little bit of bad luck. That’s the way these things go — torrid hot streaks are generally performance + luck, and deep slumps are generally performance + luck. Now let’s go past that. Harper reached his new level last season, so this is a plot of how he’s produced, since the start of last season, based on pitch locations:

Harper has been at his best over the plate, and also up and away. He’s acknowledged this before, and it’s nothing unusual. Pulling from Baseball Savant, here’s how Harper was pitched this year before the slump:

That’s an awful lot of activity in the danger zones. Harper, very obviously, took advantage of the opportunities he was given. Now here’s how Harper was pitched during the slump:

You see that? It’s not even subtle. Harper’s slump coincides with a different attack. Opponents haven’t strayed much over the middle, and they’ve mostly stayed down. It’s not like anyone has ever not tried to pitch Harper carefully, but pitchers lately have been more successful with their execution. And, yeah, the mix has changed some. Earlier, Harper ranked in the 44th percentile in terms of fastball rate. Slumping Harper ranked in the 5th percentile.

Pitchers threw Harper fewer fastballs, opting for a lot of changeups, explaining the move toward the down-away quadrant. And with more secondary stuff, pitchers were just throwing Harper fewer options in the zone. Harper, usually, is sufficiently disciplined to stay away from would-be balls, but pitchers suddenly started throwing better would-be balls, and Harper simultaneously grew a little frustrated because of his slump. So then you have pitchers working carefully, and Harper expanding the zone on himself. The way out of it, if you’re Harper, is to tighten up that impatience. Even just a matter of some deep breaths. It’s not like Harper is incapable of slamming offspeed stuff. He’d just need to let the pitches come to him, without letting frustration cloud judgment.

To boil it all down: I think this is pretty simple. I think that, during Harper’s slump, he was seeing unusually quality pitches. I think the pitchers executed more than they typically do, and I think this is probably underneath a number of run-of-the-mill offensive slumps. For a week or so, pitchers mostly avoided Harper’s hot spots, and while pitchers are always trying to avoid Harper’s hot spots, their command isn’t that good, not all of the time. This was just a good run, and Harper helped his opponents out by chasing from time to time. Chasing keeps them from having to come back into the zone with fastballs. Stand in with less frustration, and opportunities will present themselves. It’s not like there’s anything wrong with Harper’s swing. He just needs to put it on the right pitches.

Wednesday, in the fifth inning, Harper went up against Dillon Gee in a Nationals blowout. Gee threw an almost perfect first-pitch curveball. He tried to come back with a second-pitch curveball, but that one was less perfect.

Pitchers make mistakes. For a little while there, they weren’t making very many of them. I don’t think it’s anything to get used to.