Sam Dyson threw the most iconic and consequential pitch of the Rangers’ 2015 season. Rangers fans already know what it is, and they should feel free to look away if the memory’s too painful. For everyone else, here you go:

Looking back, it makes sense that Dyson was on the mound for that moment. He’d been the Rangers’ best reliever since he arrived in Texas at the trade deadline: a 1.15 ERA and a 7.5 K/BB ratio in a staggering 31.1 regular-season innings over two months, all while sporting the aggressive posture and Bloody Mary–colored beard of a Proven Closer.

But before he arrived in Texas, Dyson was just some dude, a hard-throwing righty with one really good pitch (his sinker) and good command in an era when such qualities are common among one-inning relievers. When we talk about relievers being fungible, the pre–July 2015 version of Dyson is what we’re talking about. The Blue Jays drafted him in the fourth round in 2010, promoted him to the majors in 2012 for two-thirds of an inning, then lost him to the Marlins on waivers that offseason. Miami sent him down to the minors to learn how to start again, then junked that experiment and turned him back into a pretty good big league reliever. On July 31, 2015, Dyson had a 105 ERA+ over 97 innings with the Marlins in parts of three seasons, and Miami dumped him off to the Rangers for two guys nobody cares about.

It’s at this point that the Rangers took a look at that one good pitch and said, “Hey, Sam, why don’t you just throw that?” In August 2015, 78 percent of Dyson’s pitches were sinkers, up from 47 percent in the first four months of 2015 and 54 percent in 2014. In fact, that’s what José Bautista hit out, a sinker that Dyson flattened out and left over the inside corner at crotch level. Nobody’s perfect.

Dyson’s sinker comes in at 95 or 96 miles an hour, and moves like he is the only big leaguer allowed to fill the ball with lead ballast before throwing it. Dyson’s posted a 186 ERA+ in 70.1 innings this year thanks in large part to that sinker, which he’s thrown more than half the time in 2016. Since taking over as the Rangers closer in May, Dyson has saved 38 games.

Dyson’s sinker has made him a legitimate closer, and only 14 months after being a fungible middle reliever, he’s the leader of a Texas bullpen full of similar pitchers.

This year, the Rangers went 95–67. They outperformed their run differential by 13 games, which is the biggest swing in either direction since the Mets underperformed their run differential by 14 games in 1993, and the biggest positive swing since the Detroit Tigers outperformed their run differential by 14 games in 1905, which was Ty Cobb’s rookie year, incidentally.

Whenever a team’s record is severely out of whack with its run differential, the most likely explanation is that when the team wins, it wins close games, but when it loses, it loses huge. Sure enough, the Rangers are 18–24 in games decided by five runs or more, but 36–11 in one-run games. Teams can run up a great record in one-run games for any number of reasons — superior tactical management, a dominant bullpen, or luck. The Rangers’ season has been so extreme that it’s probably a little bit of each, along with, I don’t know, are they building an artificial black hole somewhere in Dallas? Wouldn’t that affect the quantum whatever to change the odds of something? I swear I saw it in Star Trek once.

Related MLB Playoff X Factors

On aggregate, the Rangers bullpen hasn’t even been that good. It’s 25th in ERA-, 29th in strikeout rate, 30th in whiff rate, and 21st in strand rate. This ain’t exactly Wetteland and Rivera we’re talking about.

But aggregate doesn’t tell the whole story, because this is very much not the bullpen Texas was supposed to go into the season with. Dyson deposed Shawn Tolleson as closer after Tolleson posted an ERA of 10.12 at the end of May. Tolleson, Luke Jackson, and former Mariners closer Tom Wilhelmsen combined to charge 71 runs to the Rangers’ account in only 69.1 innings, while Dyson, Tony Barnette, and Matt Bush allowed only 53 runs in 192.1 innings. The latter trio, along with midseason acquisition Jeremy Jeffress and lefties Álex Claudio and Jake Diekman, will be pitching the high-leverage innings for Texas this postseason.

Since the All-Star break — by which point Tolleson had become a mop-up guy en route to the 60-day DL, Jackson was in Double-A (he was recalled on Monday), and Wilhelmsen had been released — the Rangers bullpen is fifth in ERA- and fourth in WPA, using mostly castoffs and afterthoughts to get there.

Of those six key relievers, only Claudio, a 27th-round pick in 2010, was with the team before last July. Diekman and Jeffress were throw-ins in trades that brought over Cole Hamels and Jonathan Lucroy, respectively. Barnette, a 32-year-old rookie, is just now back from six years in Japan. And then there’s Bush.

A former no. 1 overall pick who converted to relief, Bush is a little more than a year removed from 39 months in prison on three felony charges related to a drunken hit-and-run that nearly killed a motorcyclist. Bush has mostly stayed out of the headlines this year, though his story surfaced again when Jeffress was himself arrested for DWI in August and spent three weeks in an inpatient rehab center before returning to the team for the last week of the season. (Out of consideration for Bush and Jeffress, the Rangers started their celebration for winning the division by spraying ginger ale instead of alcohol.)

Everyone in the Texas bullpen throws hard, but they’re not big on strikeouts. Of those six key relievers, only Diekman struck out more than a batter an inning. Dyson’s K/9 ratio of 7.0 is below average for any pitcher, and practically unheard of for an elite closer in this day and age. This year, 22 pitchers recorded 20 or more saves, and Dyson ranks 19th among them in strikeout rate. One of the three pitchers who trails him is Jeffress.

Instead, the Rangers bullpen does two things particularly well: (1) It has great control; only Diekman walked more than 2.9 batters per nine innings this year. (2) It’s better than any other bullpen in the game at keeping the ball on the ground. Dyson, Jeffress, and Claudio all had ground ball rates north of 60 percent this year, which puts the ball in the hands of the excellent defensive infield of Elvis Andrus, Adrián Beltré, and Rougned Odor. It’s a clear path to victory, if not the most popular one at the moment.

Related The Rangers Might Have the Best Hitting Prospect in Baseball

Here’s the catch: I have no idea how much the Rangers’ new-model, ground ball–heavy bullpen can account for that 13-game gap, or how that unit (among which only Diekman and Dyson have playoff experience) will hold up in October. I like that it’s a deep group, and that Barnette is used to multiple-inning stints, because after Hamels and Yu Darvish, the Rangers rotation gets bleak quickly. I also like that even though Dyson and Jeffress have sizable platoon splits, manager Jeff Banister has two tough lefties to call on.

The Rangers have a lot going for them — Hamels and Darvish, a patient lineup stacked top to bottom with power hitters — but they don’t have anything as impactful as Boston’s lineup or Chicago’s rotation. Instead, there’s a significant chance that this postseason will be decided the same way last year’s was: Will the infield defense hold up well enough for Dyson’s ground ball–heavy strategy to work? Or will he flatten out a belt-high sinker to the wrong guy at the wrong time?