The Astros never really needed the bullpen help, you know.
For whatever reason, it feels like the Houston bullpen hasn't received a great deal of respect this year. Maybe it's because closer Ken Giles followed up his October struggles with a 4.99 ERA, a Minor League demotion and a trade to Toronto. Maybe it's because Chris Devenski, a hero in 2016-'17, gave up eight runs without getting an out across two July outings before going on the disabled list, or because Justin Verlander and Gerrit Cole were taking up all the pitching attention, or because, first the Mariners and then the A's made the American League West feel like a race.
That is, of course, incorrect. Houston relievers rank first or second in nearly every important metric -- ERA, hard-hit rate, strikeout rate, walk rate, weighted on-base, you name it -- as they have all season. This has been a good, arguably great, bullpen group.
Despite that solid base, the Astros went out in late July and traded with an American League team for a righty reliever, one who has been fantastic since arriving in Houston, and who is going to make a big difference in October. They strengthened a strength.
No, we're not talking about Roberto Osuna. We're talking about a 29-year-old righty who had been toiling mostly anonymously in the Minnesota bullpen since 2013, a guy who has one career save, who arrived in Houston with a 3.75 career ERA. We're talking about Thomas Pressly. He's the best pitcher you don't know. He's the Astros' secret weapon headed into the playoffs. It's time to know him.

Since joining the Astros, Pressly has struck out 22, without a walk. He has a 1.15 ERA; he's been unscored upon in 14 of his 16 Houston appearances. Back in 2013, he had a strikeout rate (15.6 percent) in the bottom 10 percent of qualified relievers. In 2018, his 34.6 percent mark puts him in the top 10 percent. Since Aug. 1, only four relievers have a higher strikeout rate than he does, and three of them are Edwin Diaz, Dellin Betances and Craig Kimbrel.
So: Who is this guy? How did he get this good? And how has Houston made him even better?
Pressly hasn't taken the traditional path to productivity, entering the game as an 11th-round pick in 2007 by the Red Sox before moving to Minnesota as a Rule 5 Draft pick in 2012, but if you were paying attention to the right places, he's been on your radar for a while for a very modern reason: He has truly elite spin rates. (Now you're starting to understand why the famously analytical Astros were interested.)
Pressly gets 3,221 RPM of spin on his curveball, but the actual number is far less important than where it ranks and what it means. So far this year, 210 pitchers have thrown at least 100 curveballs, and that number is the second-highest in baseball, although you could reasonably say he has the highest curveball spin of any active pitcher, since Garrett Richards, who was slightly ahead of him and won't pitch again until at least 2020 after Tommy John surgery.

High spin doesn't automatically make you successful, just like high velocity doesn't guarantee you success. Like velocity, it's a strong tool to have; difficult to teach, valuable to harness. On a curveball, high spin can help increase the movement of the pitch, depending on the angle you release the ball. You've probably heard Mets righty Seth Lugo's name come up in relation to this before; as we explored with him, there is somewhat of a relationship between high curveball spin, lower slugging, and higher strikeouts. Spin is a good thing to have, provided you know how to use it.
In Pressly's case, because of the axis he puts on the ball, his spin isn't so much about propelling drop (though he gets that, too) as it is about horizontal break. Looking at Statcast™ numbers, including the effects of gravity, Pressly's curveball moves about 17 inches horizontally, which is good, but not elite by itself. However, since gravity requires time, we can't just compare his movement to slower curves, like Tyler Olson's nearly nine-miles-slower breaker. Instead, we compare pitch movement to other pitches within a plus-two/minus-two velocity range, and doing it that way, no one gets the relative movement Pressly does. This is the spin, in action.

He's got elite four-seam spin, too, ranking in the top 10, and that's also a good thing. High four-seam spin, when used right, can lead to the "rising fastball" effect and be correlated with swinging strikes and popups.
But Pressly has always had this spin, or least we assume he did in the pre-Statcast™ days. Why wasn't he always this successful? Part of it was health, as he lost much of 2015 to a lat strain. Part of it was an increase in velocity, as he went from throwing 93-94 mph when he first came up to nearly 96 mph this year. Part of it was control; after throwing his curve in the zone only 34 percent of the time in 2016 and 39 percent last year, he's up to 49 percent this year, forcing hitters to think about it more.
He was already having a good season with the Twins, is the point. It's just taken on a new life with the Astros. Here's why.
Improving in the most Houston way possible
"Pressly was one of the best acquisitions that any team made at the Deadline," Astros general manager Jeff Luhnow said on MLB Network Radio's Power Alley show on Thursday morning, and while he's got an obvious bias there, he's not wrong.
"We've always liked him," Luhnow continued. "A lot of the feedback that we get comes from our hitters and we had played Minnesota earlier in the season, and they had mentioned that they were having trouble seeing and making contact with his stuff. We've tracked him all year, and we really like the way his repertoire is. He's been terrific, he's been amazing and he's going to have some really high-leverage innings for us going forward."
Based on what they'd seen with Minnesota, the Astros made some pretty obvious changes to Pressly. After seeing what they did with Cole, Charlie Morton and others, they're about the most "Astros" changes they could have made.

Pressly is throwing fewer fastballs. He threw 47 percent heaters with the Twins, and just 35 percent with the Astros.
Pressley is throwing more high fastballs. Sounds familiar, right? He threw his fastballs high (upper third of the zone, or higher) 36 percent of the time with the Twins, and now it's 47 percent with the Astros.
Pressly is throwing more curveballs. Obviously. After throwing his curve only 24 percent of the time with the Twins, he's using it now 37 percent of the time in Houston.
Now, take all of that, and realize that only five pitchers, including Noah Syndergaard and Jacob deGrom, throw their sliders harder than his 89.7 mph. It's an incredible package of talent, and it's finally coming together.
"Once he fully gets it, he'll take off because he has ridiculous stuff," former Twins teammate Brandon Kintzler said about Pressly before the 2017 season.
We're starting to see what that looks like. The Astros have a great bullpen, one so deep that one of Devenski, Will Harris and Tony Sipp might not even make a potential playoff roster. Pressly might be the real difference-maker, and he's finally learned how to use all that spin and velocity together.