Is Kenley Jansen “back?” It might depend entirely on if you think he was ever gone. But yes: Early on, it sure looks like he’s back.

From a saves point of view, you’re probably wondering what we’re even talking about, because just last year, Jansen’s 41 saves led the National League. “Back,” you’re possibly saying. “Where did he go?” He became the seventh pitcher with at least 400 saves when he closed out the Braves on Wednesday night, further solidifying what seems increasingly like a strong-if-not-no-doubt Hall of Fame case.

Yet from a more underlying point of view, the last five seasons were more good than great, with notable changes in both pitch mix (fewer cutters) and velocity (regularly trending downward). As time continues to remain undefeated, and as Jansen turned 35 last September, it was reasonable to expect more of the same – that he’d be a quality reliever for Boston, which signed him to a two-year deal this offseason, but that the Good Old Days were mostly over.

The Good Old Days, it turns out, aren’t over.

Instead, Jansen’s 36% strikeout rate is higher than it’s been since 2017. He hasn't allowed a homer yet. After a few years toying with sliders and sinkers as much as a third of the time, he’s back to the roughly 80% cutter usage he had at his peak. And that vaunted cutter, the one he’s riding to Cooperstown, the one that had fallen to a mere 90.9 mph in 2020? He’s up nearly 4 mph since then, and up 2.5 mph since last year. He’s actually throwing it harder than ever.

So what’s happening here? He's been around for so long that you could reasonably position this as Jansen’s fourth act:

1. The young Minor League catcher who couldn’t hit (2005-09)
2. The dominating cutter god (2010-17)
3. The solid if somewhat aging star trying to adapt (2018-22)
4. Whatever this, at age 35, is (2023)

To really explain what we mean by the difference between 2010-17 and 2018-22 here, look at what was happening under the hood, beyond the simple piling up of saves. (All stats below are entering Wednesday's action.)

2010-17 (age 22-29)

• 2.08 ERA // 40% K
• 82% cutter usage (at 93.4 mph)

2018-22 (age 30-34)

• 3.08 ERA // 31% K
• 69% cutter usage (at 92 mph)

2023 (age 35)

• 0.84 ERA // 36% K
• 80% cutter usage (at 94.7 mph)

No, he’s not really a 0.84 ERA quality pitcher, and he won't be going forward. But he’s definitely pitching like a great reliever again – and in ways we haven’t seen in a number of years. We've got three things to watch for.

1. The velocity (re)gains seem real

OK, so the velocity is up. But how?

It’s not just a good few weeks; it’s near his best month ever. Jansen has thrown at least 25 cutters in a month 71 different times over his long career, and if you rank all of those by cutter velocity, you’ll see his first two months with Boston both appearing in the top five. In May, so far, he’s throwing harder than he has in nearly a decade.

Which, you’ll be unsurprised to learn, is a key indicator of whether or not Jansen is going to be successful or not. Over his career, his average cutter is 93.4 mph, so let’s use that as a rough dividing line. You already knew he was going to be more successful the harder he threw. What might have been surprising is how big the difference has been.

Jansen, cutters 93+ mph
.148/.202/.224, 45% K rate

Jansen, cutters 92- mph
.262/.369/.466, 16% K rate

“A lot of stretching this offseason, putting my hips in better positions,” Jansen said after his first home save last month. “Opening up my [thoracic] spine through all that and also just watching a lot of videos from 2012, ’13, ’14 to see how my body was into it.”

We might not exactly have metrics for “hip position” or “spine straightness” – not yet, anyway – but it’s not the first time he’s said something like that. In 2021, when he was adding +1.6 mph over his down 2020, he also mentioned changes in his hips, the benefit of intensive offseason workouts. Given that knowledge, there’s one pretty obvious thing that he’s doing differently – and it’s about how he’s releasing the ball.

2. He's moving his body differently ...

If the hips and spine are moving differently, you’d think that the arm would follow suit, right? That’s exactly what’s happened. In his best years, Jansen would release the ball just over 6 feet high and just over 2 feet towards the third-base side of the mound (from the center). Last year, that was all the way up to 6.7 feet high and barely more than 1 foot towards the third-base side.

This year? It’s down to 6.3 feet, and 2.1 feet. Since that’s a lot of numbers – and because he’s pitched in Philadelphia in each of the last two seasons – it’s easier to just show you.

Not hard to see the difference there, is it? Last year, the arm was almost straight up. This year, it's considerably more angled.

The takeaway here is this: He’s releasing the ball a foot closer to third base than he did a year ago, and several inches lower, too. It's not like 2022 at all; it's a lot more like 2017 or the years before it. If, as Jansen says, he was watching old videos trying to see how his body worked back then ... it seems he's done that.

3. … and the cutter is moving differently, too.

We’re not just talking about “more quickly to the plate,” although obviously it’s also that. Just look at how his manager talks about it:

“His stuff is kind of invisible, to be honest with you,” said Boston skipper Alex Cora in April. “The other day, I stood in the bullpen and I saw it and I was like, ‘Wow. It's just a different pitch.’ At this velocity, it’s impressive.”

It’s still a cutter, but it’s a very different looking cutter than the kind we’ve seen from him before. Jansen used to have the kind of late-breaking cutter that, well, cut, and made the batter wonder where the ball he just swung at ended up. The 2023 version of this pitch breaks just three inches on the way to the plate – or barely a third of the 8 inches of break he had a year ago.

What he’s done is to trade it in for more rise, which is in part due to the added velo; either way, it’s got 35% more rise than other cutters in this range. You can see just how good hitters like Kyle Schwarber, Trea Turner, Shohei Ohtani and Max Kepler end up swinging under the pitch.

So: is Jansen “back?” It’s easy to want to put too much into 10 2/3 innings given his track record – again, he’s highly likely to end up in Cooperstown – and what we’ve seen so far. Of course, the one thing we know absolutely won’t change is that come September, he’ll be 36.

But know this, at least. Headed into the season, it was an open question as to whether Jansen, long one of baseball’s slowest workers, would be able to adapt to the new pitch timer rules. So far, he hasn’t had a single violation. We didn’t mention it once, until just now. He hasn’t lost velocity; he’s gained it. Whatever he’s doing, it’s working. It looks just like old times.