Kyle Hendricks has been a marvel of a pitcher the last couple years. Amid the never-ending war between batter and pitcher that has seen steadily climbing velocities both out of the hand and off the bat, Hendricks has been an outlier. He lives off guile and trickery rather than sheer power. His race for a Cy Young in 2016 was incredible as he stood shoulder to shoulder with some of the best in the game.

But things have changed. The Cubs as a whole are underperforming a bit, but Hendricks himself has fallen quite a ways from the heights of 2016 and even his very good 2017. Hendricks has lived on the fringes in his short career – the fringes of the strike zone, the fringes of viable velocity, and the relative fringes of an awards race (third place, but still). This year is a career worst for him in almost every category. And it could be for one simple reason. Whether through an internal decline or the evolution of the game itself, Hendricks has simply lost his sinker.

The sinker as a whole has kind of gone out of vogue the last couple years. It and its cousin the two-seamer have seen a relative drop-off in usage, the sinker peaking in 2012 at 9.8 percent of pitches thrown according to Pitch F/X and now falling to 5.6 percent last year and 6.8 percent this year, the two-seam peaking in 2014 at 14.7 percent and now down to 12.6 percent. It’s hard to say for sure why. Perhaps the chase for velocity has highlighted the four-seam more, maybe teams lately have valued true breaking pitches that elicit swings and misses rather than weak contact. These two attributes – velo and swinging strikes – are not in Hendricks’ repertoire. His 10 percent swinging strike rate ranked 96th in 2016, and this year at 8.8 percent he’s down to 161st. That just happens to be the same as Dallas Keuchel, another semi-struggling sinkerballer with an elite stretch in his past.

In terms of the numbers against the sinker, he’s simply being annihilated this year:

Hendricks sinker performance by year Year wRC+ GB% HR/FB% O-Swing% Avg. Velo(mph) Usage Year wRC+ GB% HR/FB% O-Swing% Avg. Velo(mph) Usage 2015 118 59.0 19.0 30.6 88.1 60.6 2016 95 56.3 10.3 22.1 88.1 42.8 2017 65 60.2 17.9 22 85.7 43.7 2018 130 48.3 18.2 20.1 86.6 46.5

So it’s always been about locating it for Hendricks. His pinpoint control is otherworldly, and his use of the edges (and perhaps just off with a good frame job or two) baffles elite hitters. His sinker heat map from 2016 illustrates his work on the fringe:

The thing is, that’s held true this year. It’s nearly identical to where he worked the most in his best season:

So evidently his command isn’t suffering, at least in a macro sense. If anything he seems to be more regularly hitting the edge. And he’s throwing the ball basically as hard as he did last year when he had a very solid (if not quite 2016 otherworldly) campaign. Still, that could have been a part of what happened with him last year too. Losing two ticks on a pitch when you’re already dealing from a deficit can be big. I watched it much more closely as the Indians’ Josh Tomlin suddenly and utterly collapsed out of the rotation and quite possibly the roster by season’s end.

There is one big change that Hendricks has dealt with since 2016. Well, two plus the velocity drop. The first is the home run rate leap, both for himself and across baseball. As the above chart shows, he’s allowed twice as many homers on his sinker, and overall his HR/FB rate has jumped from 9.6 that season to 16.7 percent this year. It’s something all pitchers have had to deal with. But perhaps just as importantly, if not more so, he’s dealing with a different lead catcher. In 2016, he pitched to four different catchers; Miguel Montero for 95.2 innings, Willson Contreras for 71.1 innings, then Tim Federowicz and David Ross for a combined 22.1 innings.

Those two main guys, Montero and Contreras, rated at +4.3 and +10.1 Framing Runs Above Average that season, respectively. That’s very helpful for a command and control guy. This year, Contreras has caught 74 of Hendricks’ 115 innings as of this writing. Contreras has also rated -11.1 FRAA so far this season. His struggles with creating strikes have been well-chronicled, and by the numbers its hurt Cubs pitching. If the numbers don’t prove it, or if you’re more a visual learner, these are the strikes Hendricks got on the edges in 2016 according to StatCast:

And here’s the edge work he’s getting this season:

It doesn’t look like he’s losing a lot of strikes at first glance, but especially down on the corners and below the zone Hendricks is losing a ball width or more on his pitches. That’s a lot of real estate no matter the pitcher, but it’s vital for his survival. The sinker being his bread and butter pitch, it’s sure to suffer the most from his inability to nibble hitters to death.

This might not all be Contreras. A shrunken strike zone can be driven by a lot of factors aside from the catcher being bad at framing. The improvement of umpires and their being judged by pitch tracking software. Bad luck. Menacing hitters that scare those improved umpires. Bad lighting…? But whatever it is- and the catcher could well be the main culprit, framing stats and other catcher ratings are still kind of nascent- it’s hurting the pitcher’s effectiveness.

If Hendricks simply holds to what he is right now for his career, he’s still bound to have a long one. He’s about a league average pitcher by ERA-, and has the ability to eat up 200ish innings per year. But it was so marvelous to see him just crush hopes with seemingly middling stuff, picking apart the most elite of batters time and again, the fact that it’s slipping away in part because of things out of his control is depressing. Contreras has noted he is working on getting better at framing, and Hendricks does still have a solid arsenal behind just his sinker. Hopefully this is a blip, because in this era of triple digit starters and reality bending curveballs, a slice and dice man is a nice change of pace.

Merritt Rohlfing writes baseball at Beyond the Boxscore, and overanalyzes the Indians at Let’s Go Tribe. He also co-hosts their podcast. It’s great. Follow him on Twitter @MerrillLunch. It’s also great.