The other day, Kenley Jansen caused a minor stir when he threw a 98 mile-per-hour cutter. In reality, Jansen had thrown that pitch before, but (A) the camera angle really showed off the movement, and (B) who cares! That’s cruel all of the time! A cutter is a non-traditional sort of fastball and Jansen threw one with well-above-average velocity. It missed the bat that tried to hit it because what alternative was there? Who hits that pitch?

That pitch got me looking at other high-velocity pitches with unusual movement. Then that line of thought got me thinking: when you’re facing Jansen, you’re looking for cutters. He throws the cutter almost all the time. He uses it as his primary fastball, so the really mean pitches might be his non-cutters. That sent me on a search and I think I might have found the most dominant, unfair Kenley Jansen relief appearance. I know it seems kind of stupid to reflect on an outing from April 20 when we’re a week into August, but think of this as a fun examination of the tools Jansen has at his disposal.

On April 20, Jansen faced three Diamondbacks in relief and he struck them all out. I didn’t actually go looking for occasions where Jansen struck out the side; this occasion found me. The results are suggestive of Jansen’s level of dominance, but it’s the sequences that really set this appearance apart. Watch what Jansen has done, and therefore can do. We’re all mesmerized by the cutter. It’s easy to forget what the cutter can set up, because we’re so busy thinking of the cutter as being lethal on its own.

Let’s begin with Miguel Montero, just like Jansen did. To go in any other order would be weird.

Here’s your run-of-the-mill 93 mile-per-hour backdoor cutter for strike one. It’s a right-handed fastball that breaks like an overhand left-handed fastball, and instead of running away, the pitch breaks toward the heart.

Another cutter that brushed Montero back a little bit. The pitch was supposed to be better — the pitch, ideally, would’ve gotten a strike — but still, Montero’s looking for cutters, and he’s getting cutters. He’s now seen cutters to both sides of the plate.

I don’t know what you’re supposed to do with a cutter high and tight. Montero felt good about what was coming, but that’s an impossible pitch to punish; he made foul contact, and that was a small victory.

Here’s where Jansen really got mean. It’s hard to see in the .gif, because Jansen throws so fast, but not only was this pitch 97 miles per hour — it was a regular fastball, not a cutter. The first pitch broke three inches toward Montero. The second pitch did the same. The third pitch was straight. This pitch ran six inches away. So where Montero thought he was getting another high and tight cutter, he wound up with an elevated fastball he couldn’t touch because his location guess was off by most of a foot. What do you do when a guy can throw 96 breaking in and 96 breaking away? Apparently you strike out. Let’s continue. Aaron Hill’s the next victim.

Cutter that Hill was taking all the way. I don’t know why — Jansen pounds the strike zone, but it’s not like Jansen is easy to hit when he grooves his pitches. A grooved Kenley Jansen pitch is not a grooved pitch at all. Maybe Hill just wanted to go one delivery without embarrassing himself.

Another cutter high and tight, in pop-up territory. Similar to the cutter Jansen threw to Montero up and in, and in that specific location there’s just no real damage that’s possible. Batters can swing because it’s a strike, but it’s one of those perfect strikes that Mariano Rivera made a career out of throwing.

And by the way, Kenley Jansen has a slider. Hill, obviously, wasn’t counting on that, so he got way out ahead and never stood a chance. Righties against Jansen see about 8% sliders, which means you can never expect to see one, and that’s why it has a contact rate close to 40%. I don’t know if Kenley Jansen has a good slider, overall. But his slider serves its purpose, specifically because it’s thrown infrequently, specifically because he’s almost all cutters. It’s the Tim Wakefield fastball effect, in a way. A decent pitch, thrown infrequently, can look like an amazing pitch. Let’s finish with Eric Chavez.

Chavez had seen two guys take first-pitch cutters for strikes, so he elected to swing away and he made the best contact of anyone. Jansen put the pitch almost down the middle, then came back to change Chavez’s eye level.

That’s a cutter at 96, and it insisted that Chavez pay attention. Aware now of the possibility of a cutter inside, Chavez was left a little vulnerable on the outside edge.

And now we’re almost finished. With many pitchers, leaving a fastball in that spot might’ve been dangerous, but as mentioned earlier, Jansen makes a habit of staying in and around the zone, high, because his cutter is so hard to hit even in hittable places. At this point Chavez had seen one cutter in, one cutter in the middle, and one cutter outside. I don’t know if he remembered what happened to Montero, but he was about to be reminded.

At 1-and-2, Jansen again went to the fastball instead of the cutter. The first pitch broke an inch in toward Chavez. The next two pitches also broke toward Chavez. The last pitch — at 98 miles per hour — ran away by more than seven inches, which is the most horizontal movement Jansen has gotten on any fastball this season. Out of Jansen’s hand, Chavez would’ve been looking for something that would break toward the heart, but instead the fastball darted out of the zone and Chavez was left helpless. At once, he’d seen new movement and new velocity.

It’s that pitch, I think, that’s more insane than Jansen’s 98 mile-per-hour cutters. When batters are looking for cutters, they’re not prepared for more ordinary-moving fastballs, so they don’t function like they’re ordinary. Over Jansen’s career, batters have slugged .264 against the cutter, and .250 against the fastball. The inning above I think really highlights the subject of Kenley Jansen and game theory — because he throws his cutter all the damned time, he’s able to make wicked use of his fastball and slider, when he chooses. Jansen already possesses a cutter unlike just about anyone else’s. It’s his primary pitch and then some, which lets him play with secondary stuff that might not be great as a couple of standalones.

There’s one thing I discovered that I wasn’t sure how to fold in. But, above, you see 98 to close an at-bat. In the inning from the other day, we saw 98 to close an at-bat. It’s been known for some time now that pitchers, on average, throw harder with two strikes, presumably in an effort to put the hitter away. Jansen, this year, is throwing two full miles per hour harder with two strikes. He’s been fairly consistent over his career, and no one in baseball this season is showing a larger differential. In putaway situations, Jansen has been reaching back for something extra, and he’s found it, and now we’ve seen what that looks like. It’s tremendously cruel, and that would be true if Jansen couldn’t make his hardest pitches move to either side.

Kenley Jansen is mean, because he can throw a guy a cutter close to a hundred miles per hour. Kenley Jansen is at his meanest when he mixes his pitches up, because you just can’t prepare for two kinds of fastballs and a breaking ball too. They say good hitting is about eliminating pitches, and with Jansen, it hasn’t helped to focus on the one pitch he throws almost all the time. It especially hasn’t helped when he hasn’t thrown it. Make no mistake: Jansen is far from a one-pitch pitcher. He just pitches like he is to set up the times that he isn’t.