About eight years ago, Tanner Roark was pitching in the independent Frontier League after his college team released him. He had an ERA greater than 20.00 in three games. Then the Rangers drafted him, traded him to the Nationals, and he switched to throwing only two-seamers as his main fastball. A few years later, he put up a three-win, 198-inning season, and now — after largely unsuccessful work out of the bullpen in 2015 — he’s a few days removed from a 15-strikeout game. The career arc was pretty tumultuous and incredible before Saturday’s game, and now it’s the sort of thing about which someone writes a book a decade afterwards.

Let’s start with a table to reinforce this day of strangeness. Below is a list of all of the 15-plus strikeout games in the past five years. There are 21 of them, from Jered Weaver’s (!) 15-K game in April of 2011 all the way up to Roark’s gem this past Saturday. Average fastball velocity displayed is for that particular 15-plus strikeout game:

Now let’s divide the games into two parts based on the average fastball velocities. We’ll bring in some strikeout and walk rates for the players/years in question to go along with velocity, too. Take a look:

Velocity/K & BB%, 15+ Strikeout Games, 2011-2015 Avg. FB Velo During Game # of Games K% of Pitchers* BB% of Pitchers* > 92 MPH 16 25.8% 7.0% < 92 MPH 5 21.6% 6.0% SOURCE: FanGraphs *Average of yearly totals for pitchers in group, 2011-2015

We see a few things right away. Some obvious things. First: speed helps! Not too surprising there. Sixteen of the 21 games featured pitchers who averaged at least 92 mph on their main fastballs during their 15-plus strikeout game. Second: the slower group has lower yearly strikeout and walk rates compared to the faster group. Among the slow sample, we have guys like Jon Lester and Cliff Lee — lefties with immaculate walk rates — and Felix Hernandez, who can throw what is basically an 88 mph screwball. These are pitchers who can’t get by on their fastballs alone, and each one has (or had) at least one great secondary offering during the year they pitched their 15-K game: Lester’s curve was fantastic in 2014. Lee had four valuable pitches in 2011. Felix had his changeup. Even Jered Weaver had a top-10 changeup by run value in 2011.

And, placed slightly awkwardly among them, there’s Roark. To say that he doesn’t have secondary pitches would be unfair; almost all major-league pitchers have at least one serviceable secondary pitch. It’s just that Roark’s secondaries have never been great — unlike the other guys with whom he shares the list. The curve he throws used to be the best of the lot, but now he leans on his slider more; his fastball and slider have combined for almost 79% of the pitches he’s thrown this year, in fact. Case in point: in his start prior to the one against the Twins on Saturday, he threw either a fastball or a slider over 90% of the time, which is the type of approach that cements your reputation as a two-pitch pitcher. Roark is, in some ways, still searching for consistently good offspeed and breaking pitches that really work for him. It’s one of the main reasons he’s in the top 20 of percentage of fastballs thrown this season.

On Saturday, however, he naturally decided to do something completely different and make his secondaries into monsters. He threw only nine sliders, he used his highest-ever percentage of changeups during a start, and his curveball was, on average, the hardest it’s ever been. Roark wasn’t a terribly different pitcher than he has been at points in the past — his pitch mix was similar to ones he used last year as a reliever — but he threw everything a little harder, and got strikeouts from every single one of his pitches. His two-seamer might be the pitch worthy of the most thorough examination, however, as it has been looking a bit different lately — not just in this past start. Take a look at the horizontal movement on his two-seamer over his career (each data point is an appearance), courtesy of Brooks Baseball:

We can see the delineation between 2015 and 2016 on the end of the right side of the chart, and the more consistent arm-side run that Roark is getting on his two-seamer this year. Now let’s bring in a video comparison. Take a look at an average two-seamer of his from 2014 vs. his start on Saturday. Here’s a close to average fastball from Roark, 2014:

And here’s an average 2016 one from Saturday:

There is never a perfect way to do this. But if we acknowledge the shortcomings inherent in comparing just two pitches, it certainly looks like Roark is getting some extra horizontal movement in 2016. Adding the extra element of command to that more effective two-seamer is when this picture starts to fully form of Saturday’s start. One way to measure it: how often Minnesota batters swung at strikes. The Twins swung at only 41.5% of pitches in the strike zone on Saturday; league average last season was above 64% (Roark’s career average is 61.3%). That led to 41% (32 of 78) of Roark’s strikes being called strikes, much higher than 2015’s league average of 26.4%. Looking at a heat map of his called strikes to right-handed hitters tells us why the Twins weren’t swinging at a lot of them:

This strike-zone box from Baseball Savant should be considered loosely correct, but we can see the execution: paint the outside corner. Stretch the zone with the two-seamer, potentially. Then, with two strikes, go to the changeup for a punch-out. Roark threw only seven changeups to right-handers on Saturday, but three of them resulted in strikeouts. For lefties, it was all two-seam fastballs up-and-in, like the second video above.It should at least be noted that the Twins had a large part to play in Roark’s success: they are looking like a more strikeout-prone club than in years past, and the 10 games of the season saw them striking out at almost a 30% rate. That’s gone down a fair amount, but we have to look at the low-contact lineup the Twins ran out against the Nationals on Saturday.

That shouldn’t bother us too much, though. If we consider only fastball velocity, guys like Tanner Roark don’t strikeout 15 batters in a game very often. The ones who do are command freaks with dynamite secondary pitches, with the latter of which Roark is still struggling. Yet here we are, two days removed from him looking absurdly dominant on the back of increased run on his fastball, a different secondary approach, and incredible command. Sometimes you make adjustments for greater success and the payoff comes slowly. Other times, it comes all at once.