There’s something odd about the Cubs’ starting rotation, and I wrote about it last week. All five pitchers have been working with reduced velocity, relative to where they were last season. When it happens to one guy, it’s a potential problem. When it happens to five guys…I suppose it’s a potential *huge* problem, but it’s also a potentially deliberate pattern. I speculated as much, offering that the Cubs might be trying to back off their main arms since they’re coming off an extended season, and preparing for another.

Jake Arrieta has been okay, reduced velocity or not. The same goes for Jon Lester, who looks like the same pitcher. However, it’s a different story when it comes to Kyle Hendricks. Like the other starters, Hendricks isn’t throwing as hard as he used to. But then, Hendricks is sitting on a 6+ ERA. He specialized in command and soft contact. Now he has worse command, and he’s allowing hard contact. As far as Hendricks is concerned, something seems awry, although it looks to me to be mechanical.

The first tip-off, of course, is that Hendricks has lost almost three miles per hour off his fastball. Although that reduced velocity doesn’t make him unique among the Cubs, it’s still enough to raise the eyebrows, especially given that Hendricks doesn’t work with a lot of heat in the first place. He has only so much to sacrifice. If Hendricks were still pitching well, we might be able to chalk this up to some kind of plan. Instead, his numbers call for a closer look.

Hendricks’ strike rate is down a few percentage points. Basically three strikes a game. It’s not surprising that he’s lost a few strikeouts, and added a few walks. This despite throwing the same number of first-pitch strikes, compared to last season. The issue hasn’t so much been getting ahead as staying and working ahead. Hendricks’ contact rate has spiked. His hard-hit rate has spiked. He’s generated just one infield fly. And, of some note, Hendricks’ elite-level changeup has so far rated as a below-average pitch. Relative to the fastballs, Hendricks’ changeup has lost one tick of separation.

Just about every indicator is bad. The situation isn’t close to catastrophic, but the Cubs would probably love to know what’s happening. We might as well look at where Hendricks has been throwing, and where he threw a season ago:

2016 on the left, 2017 on the right. There is a shift! I don’t know whether it’s intentional or accidental. The recent version of Hendricks has thrown an awful lot more pitches around the arm-side edge. We knew his location was different; this is the way in which it is different. We have a pitcher throwing to different spots, with considerably less-powerful stuff.

Why? From the outside, I can never dismiss the injury idea. I simply don’t know enough. I can’t know enough. That being said, Hendricks hasn’t suggested he’s feeling any discomfort. The Cubs don’t seem like they’re hiding anything. My hunch is that a minor mechanical problem has knocked Hendricks sideways, so to speak. Effective pitching all comes down to proper timing, and it looks like Hendricks’ timing is off.

Here is a pitch from last September:

Here is a pitch from last week:

It’s clear that we’re seeing the same pitcher in both clips. Hendricks has a fairly distinctive wind-up, and there’s no mistaking him. But something small has changed. It’s never entirely fair to compare any two deliveries, since the sample size is so small, and one pitch isn’t necessarily representative. It’s also impossible to compare every delivery. Will you settle for three? Here are six screenshots — three from the September game, and three from Hendricks’ most recent game.

Look at the back foot, the one on the rubber. In the shots from last September, the foot creates a line that’s basically perpendicular to the ground. Straight up and down. In the shots from last week, the foot is at an angle. Maybe we’ll call it 45 degrees? Hendricks’ ankle is turned inward, as in these shots, he’s kind of still pushing off.

As a different way to visualize it, here are two Hendricks deliveries side-by-side, when the ball is in about the same position:

You see the difference in the feet. Now, here’s another side-by-side comparison, keeping the same shot from the left. This shows when his foot is in the same position:

In Hendricks’ recent game, his back foot still achieved that briefly perpendicular alignment. That’s part of his throwing motion. But look at where the ball is in each screenshot here. On the left, it’s behind his head, and so is his elbow. On the right, it’s coming out from behind his head, and his elbow is already surging forward. So, actually, forget the ball and focus on the elbow. Hendricks’ back foot is coming up later in his motion. I don’t have good-enough video to analyze much deeper than this, but it suggests that Hendricks is staying on his back leg a hair or two too long. Maybe he’s taking a little too long to plant his front leg. Maybe he’s not achieving quite the same shoulder rotation. The transfer of energy isn’t as efficient as it was, and that’s all it takes to lose a couple of miles. You don’t always have to worry about something structural, when it’s so much easier for a throwing motion to just go a little out of whack.

Of course, there’s plenty of room for me to be wrong. And, of course, a mechanical issue comes with no guarantee of quick or successful resolution. These things can be hard to fix, even when they’re subtle, barely noticeable. But for Kyle Hendricks and the Cubs, it’s April, and he’s got all kinds of time to work out any kinks. Maybe it’s encouraging that, this spring training, Hendricks’ fastball was averaging 87. That’s where he was last April, so this could just be a minor slip-up. Take nothing for granted, but appreciate how good Hendricks became, such that a short slump like this gets the attention it does.