The Twins are undeniably one of the most exciting stories of the year. They’ve hit, and I’m approximating here, eighteen million home runs on their charge to the top of the AL Central, holding off the Indians with burst after burst of offense. Their starters are deep and talented — Martín Pérez, whose resurgence has been a fun story, is their fifth-best starter by WAR, with 1.8. José Berríos keys the unit, but Jake Odorizzi, Kyle Gibson, and Michael Pineda are all having excellent seasons.

While all the sluggers and starters have top billing on the team this year, their bullpen has been quietly excellent. They’ve been the second-best group in baseball by WAR this year, the best by FIP-, and have walked batters less frequently than any other relief corps. If win probability added is more your speed, they’re eighth in the league. A year after being below average across the board, their sterling last 30 days (3.24 ERA, 3.30 FIP, 1.6 WAR) has helped the Twins remain atop the AL Central after a brief swoon.

But calling it a group effort is misleading. They’re a group, to be sure — seven relievers with at least 20 innings pitched have posted park-adjusted FIPs and ERAs better than league average. They’re more Derek and the Dominos or the White Stripes than a true group, though. Taylor Rogers is the rock of the group, a bona fide stopper putting up his second straight dominant year of relief. He’s still best known for having a twin brother in the majors, but maybe it’s time he’s known more for his pitching than his family.

You’re skeptical, and that’s fine. Taylor Rogers is good and all, but he’s not in the discussion for best relievers in baseball, right? Well, take a look at the top 10 relievers of the past two years by WAR:

Okay, fine, FIP likes him. FIP is for losers who want to look at their underlying stats instead of counting runs and rings, though. How does he stack up in RA9-WAR?

Yeah, Rogers is great. He’s even sixth in win probability added over the past two years for relievers despite only becoming the team’s closer this year, which means he’s not delivering his stats in meaningless situations. He’s simply excellent, no matter how you slice it.

So why haven’t you heard of Rogers? The overarching reason is that he wasn’t always this good. Rogers was one of those marginal lefty relievers every system seems to have a few of, 16th on the 2016 Twins prospect list. What little shine he had was as a lefty specialist, and that talent brought him to the majors in 2016.

In 2016 and 2017, Rogers was just that. He allowed a .243 wOBA to lefties and a .336 wOBA to righties, which made him a nice addition to the Twins bullpen but not much more than that. The team wasn’t even particularly good at getting him in to face lefties,which left his overall stat line lacking — a 3.82 FIP, 22.6% strikeout rate, and 7.4% walk rate doesn’t scream closer stuff.

A few years of mediocre relief work is a great reason not to believe a breakout. For every Kirby Yates-style journeyman who becomes dominant, there are a dozen 2018 Craig Stammen or 2017 Anthony Swarzak counter-examples. Relievers have one-off amazing seasons all the time, and it rarely lasts. Rogers blitzed through 2018 with a 2.63 ERA and 2.33 FIP, setting down lefties (.202 wOBA) and righties (.267 wOBA) alike. His strikeout rate jumped to 28.9%, his walk rate fell to 6.2%, and the team did a better job playing him against lefties, which improved his overall line.

If that’s all that had changed, there would be good reason to be skeptical. But under the hood, more was going on. In May of 2018, Rogers completely changed who he was as a pitcher:

Aside from some light dabbling with a slider in 2016, Rogers used his curveball and two-seam fastball almost exclusively. There’s reason to believe, in fact, that those 2016 sliders were miscategorized curves and that 2018 was the first time he threw a slider in games.

The new pitch, a mid-80s dart that blended well with his existing two-seam, was an immediate success. Halfway through June, he was throwing it a quarter of the time, cutting into curveballs and sinkers equally. It was a setup pitch, an out pitch, whatever Rogers needed — the pitch seemingly arrived fully formed.

As amazing as that sounds, there was a sound reason behind its immediate success. Rogers simply retooled his curveball, changing release and arm action slightly without altering the grip. “That’s familiar. Less fumbling around with the ball and tipping pitches,” he told Dan Hayes last September, talking about how he’d been able to integrate the pitch so quickly.

One odd quirk of the slider is that Rogers uses it to keep righties off-balance. Sliders generally display large platoon splits due to their horizontal run away from same-handed batters. In 2019, sliders thrown by lefties have a 35-point wOBA platoon split, as compared to 7 points for curveballs. Rogers has an excellent downward-breaking curve, the type that’s toughest in theory for righties to pick up.

That’s all theory. In practice, Rogers is downright excellent at burying the slider low and in to righties. He showed off his command of the pitch by bamboozling Mike Trout earlier this year:

His delivery and arm action do a good job setting righties up to see and think fastball, and the pitch does the rest. His 13.7% swinging strike rate on a left-handed slider thrown to righties is among the best in the league, comparable to Aroldis Chapman, Clayton Kershaw, and Chris Sale.

In addition, an extra breaking pitch makes his curveball more useful. When a batter picks up spin, Rogers could be throwing either pitch, or something in between the two, and yet his average curve drops eight inches more on its flight to home plate than his slider. That uncertainty helps get Gleyber Torres to wave through the curve here:

Rogers set Torres up with a slider low and in, a fastball high and away, and finally the below-the-zone curve, and the variety left Torres guessing. Even if the slider didn’t directly lead to a strikeout, it played a valuable part in the at-bat, flattering the pitches around it.

Oh yeah — the velo helps, too. Rogers sat in the low 90s when he was drafted by the Twins as a starter, and even after a relief conversion, he averaged around 93 mph on his fastball when first called up. With his delivery aiding his deception, he could get by with that roughly average velocity, but he couldn’t thrive. Over the past two years, he’s added strength and velocity. The pitch is up to 95 mph on average, and he’s topped out above 97 this year. What was once a reasonably average fastball is now comfortably plus.

Put it all together, and there’s no reason to think Rogers shouldn’t continue to succeed. His new slider and curveball blend well, and they complement his sinker nicely. His breaking balls allow an 80th-percentile rate of wOBA and xwOBA on contact, where higher is better for the pitcher. They induce whiffs on 36% of swings. The sinker generates 58% ground balls, protecting him from a homer-mad league. The whole package combines to be more than the individual parts, and the individual parts are all pretty nice anyway.

The bottom line is that Rogers is an absolute stud now. He’s in the 90th percentile of xwOBA allowed and the 80th for wOBA allowed. His strikeout rate has climbed from the low 20s in 2017 to 32.1%, while his walk rate has dipped to a minuscule 4.2%. His platoon splits have been weird this year — he’s having his worst season against lefties at the same time he’s having his best season against righties — but with lefties batting an anemic .199/.266/.256 against him in his career, there’s little reason to worry he’s suddenly less capable of getting them out. He can pitch more than an inning if needed, something he’s already done 15 times this year. Essentially, he’s everything you want.

This could all end tomorrow. Rogers is a reliever, which means he’s high risk — you never know who will be 2018 Edwin Díaz and who will be 2019 Edwin Díaz. But right now, right this minute, he’s absolutely one of the best relievers in baseball. When the Twins take a lead into the ninth, they might not have the name recognition of a Josh Hader or an Aroldis Chapman, but when it comes to results, what they have is as good as it gets.