PITTSBURGH — FanGraphs alum and MLB.com analyst Mike Petriello authored the following tweet last October. The social-media missive is pinned to his Twitter profile — and rightfully so, because it’s funny, and humor is often rooted in some truth.

pssst it's a cutter pic.twitter.com/uKNI8HUeyD — Mike Petriello (@mike_petriello) October 19, 2016

The truth, in this case, is that Kenley Jansen has dominated with one pitch like few before him — specifically, with a cutter that he’s thrown 86.0% of the time this year and 88.4% of the time over his carer. Jansen’s usage has invited natural comparisons to Mariano Rivera’s own approach for years. Jansen has become dominant in Rivera-like fashion and now just requires ultimate postseason success to further raise his profile.

I showed Jansen the tweet recently in the visiting clubhouse at PNC Park. To get a better look, he took my iPhone in his massive catcher’s mitt of a left hand and examined it. He could have crushed it like a soda can and returned the fragments to me. I waited in suspense for his reaction.

Seated before his locker, he eventually smiled before passing the phone back.

What was Jansen discussing in that moment last October?

“I don’t know. It’s been too long now, you know?” Jansen said. “A lot of innings have gone by. It might be changing signs, I would say.”

But this idea that Jansen throws and dominate with one pitch also seems to be mildly offensive to the relief ace.

“One pitch because becomes four pitches,” Jansen told FanGraphs.

Oh?

“Why [do] I say four? Because, I’m really working on my location, understanding throwing hard is not the thing in the big leagues,” Jansen said. “Down and away, up and away, up and in, down and in… [Then] one pitch basically is four pitches. Add in the two-seamer, plus the slider, and it becomes six. That’s how I see it.”

Jansen, of course, has dramatically improved his location.

After walking 11.9% of batters in 2011 and 8.7% of them in 2012, the right-hander has continued to refine his command. He recorded just a 4.4% walk rate last year. And this one? After facing 112 batters without a walk to begin the season — 51 of whom he struck out — Jansen has produced just a 2.8% mark. As you might imagine, his 51-strikeout, no-walk stretch is an MLB record.

“The last two years, I started to really work on my location,” Jansen said. “You can see the last three years my walk rates are way down. I’m really working on my location. Who knows how hard I am going to throw five, 10 years from now?… One thing you can control is how you locate your ball. Guys like Gonzo [Adrian Gonzalez] and Turner [Justin Turner] will tell you a ball that cuts and moves and is located well is harder to hit.”

If that isn’t enough to convince you that Jansen is improving, consider his ability to locate in extreme portions of the strike zone. The following are the percentage rates in which Jansen has located his cutter to the extreme up-and-in, down-and-in, up-and-away and down-and-away locations, according to the Baseball Savant detailed zones:

Four corners versus left-handed hitters:

2015: 3.0%

2016: 2.8%

2017: 4.0%

Four corners versus right-handed hitters:

2015: 3.7%

2016: 2.7%

2017: 4.5%

So while a mound visit for a pitcher who dominates so thoroughly with just one pitch might seem unnecessary, Jansen says communication does serve a purpose, since the Dodgers have signs for in or away, but not for up and down.

“Sometimes when I call [catchers] out, I will say ‘I want to go up and away,’” Jansen said. “They won’t put a sign down because they already know what’s coming. I might tell them, ‘Hey, for this pitch and the next pitch, if [the first pitch] is for a ball I will do this, if it is for a strike I will do this.’ So for two pitches, we won’t put a sign down. That’s how we go sometimes. You have to study the hitter and understand the weaknesses.”

Jansen has heard the comps to Rivera throughout his career, but he has begun to take them more seriously. He has watched more and more video of Rivera over the last several years and has marveled at his command and how he set up batters.

“The way I say command, you start making guys chase,” Jansen said. “You can’t be scared to throw behind in the count. You see the great Mariano Rivera, he could always command any side of the plate. By watching him, it kind of wakes me up: ‘If I can work on my command, it will be fantastic, it will be fun out there.’”

Of course, Jansen has rarely been behind in the count this season. His first-pitch strike rate is at career-high 73.9% and up nearly six percentage points from last season. But his zone percentage has remained steady at 55.9%, which is almost precisely the same as his career rate and his rate from last season. Jansen’s formula this year is to get ahead early and then expand.

“Whenever I go fastball in, then I want to go more in, and see if hitter chases,” Jansen said. “When he is so geared up for that,t I will go away and it runs back over the plate.

“I went through that run [51 strikeouts to no walks] because I wasn’t afraid to throw balls. I trusted myself that I can throw a strike whenever I wanted to. I go in the zone, and then I will be out of the zone.”

The following video evidence is of Jansen getting ahead and expanding against Brandon Crawford:

Here’s an illustration of Jansen beginning in the zone and trying to widen it from a recent game against the Pirates.

Good morning.

Good afternoon.

Good night.

As we can see, Dodgers catcher Yasmani Grandal began with a target lower and over the plate and raised it higher and more away in the next two pitches. While the locations were not perfect, the intent was there.

So while it might seem, from the outside, that Jansen has a relatively simple formula, he has mastered his craft. And it is from simplicity that comes sophistication. Jansen is living, dominating proof of that.