Something happened the other day that hadn’t happened in nearly 17 years, and had only happened twice in the last 50. Not counting Little League, I mean. It happens all the time in Little League. It happens in Little League because catchers aren’t great at catching the baseball, relatively speaking. Little League catchers aren’t great at catching the baseball, and there’s a (bizarre?) rule where batters can attempt to advance on dropped third strikes, and so we’ve all seen plenty of batters reach on strikeouts while we sigh from our positions on the field and wonder how we’re going to sneak out of our friend Gabe’s house to hang out with the girls across the street once Gabe’s parents go to sleep later that night. And then we hope our team’s pitcher strikes out the rest of the guys, too, because striking out more batters than there are outs in an inning is fun.

But it doesn’t happen as often in the big leagues, because, y’know, catchers are good. When it does happen, it’s usually because the pitcher’s stuff is so nasty that it becomes difficult to catch, even for the catcher. When it does happen, it’s also usually four batters in one inning. It’s rare, but it happens. Using the Baseball-Reference Play Index, I ran a search spanning the expansion era, looking for relief outings of exactly one inning with at least four strikeouts.

The results of that search:

Dating back to at least 1985, there are 19 instances of a pitcher whose entire outing consisted of one inning, and four strikeouts. There are plenty more instances of four-strikeout innings, of course, mixed in with the rest of a relief outing, but these are the only guys with one, clean, four-strikeout inning. Nineteen different guys, although two of them are named Mike Stanton.

I ran another search, looking for five strikeouts over 1.1 innings. Nada. Then again, for six strikeouts over 1.2. Results!

There’s our guy. Ken Giles got five outs against the Texas Rangers the other night. Six of them were strikeouts. That line — six strikeouts in 1.2 innings — hadn’t happened in almost 17 years. Before that, it hadn’t happened in a week. Weird.

Funny enough, Giles’ outing couldn’t have began much more inauspiciously. The first batter he faced, Jurickson Profar, lined a double into the right-field corner on the second pitch, scoring two runs and putting the Astros in a three-run hole.

The pitch was a fastball:

The fastball led to an unfavorable result. So Giles went to the slider. His first strikeout victim was Rougned Odor. The entirety of that at-bat looked like this:

Slider, buried, for a swinging strike one. Slider, buried, for a swinging strike two. Slider, buried, for a swinging strike three. Giles didn’t even let Odor see the pitch that just burned him. Odor didn’t even let Odor get a chance to see it.

The next batter, Jonathan Lucroy, struck out on this pitch:

You should be starting to notice a pattern here. The pattern isn’t just “Ken Giles throws a bunch of sliders.” The pattern isn’t even “Ken Giles throws a bunch of sliders and gets a bunch of swings and misses.” The pattern is “Ken Giles throws a bunch of perfect sliders.” A perfect slider, in this case, winds up in the dirt or inches above the dirt. A perfect slider can’t be touched. Every pitch you’ve seen in this post so far has been just about a perfect slider. No swing is ever making contact with these pitches.

The catch-22 is that, when a slider gets spotted in the dirt, it becomes harder for the catcher to corral. Jason Castro couldn’t even hold onto that last one against Lucroy after he caught it.

To further complicate things, Giles came out for the next inning, and Castro didn’t. Castro was pinch-hit for in the bottom of the eighth, so the Astros in the ninth gave up the designated hitter by putting Evan Gattis at catcher. Gattis, to begin with, isn’t a great defensive catcher. More specifically, Gattis isn’t a great blocking catcher. Over at Baseball Prospectus, they keep track of all kinds of catcher defense stats, including blocking runs above and below average as well as blocking chances. A full-time catcher can receive up to 5,000 blocking chances in a season. Take every catcher this year and prorate their runs to 5,000 chances, and Brian McCann is your top blocker, at +1.1 runs saved. Castro is tied for fifth, at +0.6 blocking runs saved. Giles had been throwing to one of baseball’s best blockers. You just saw him smother four sliders. Then Gattis came in. This is where Gattis ranks:

Blocking runs per 5,000 chances, all 2016 catchers, bottom five

In swapping Castro for Gattis, the Astros went from a top-five blocking catcher to baseball’s worst. Here’s the first Giles-to-Gattis strikeout of the night:

So that’s how we get our extra out. Giles’ slider: too good. Gattis’ blocking ability: too bad. A lethal combination, for both batter and battery.

Giles hits the next batter, with a fastball. Back to the slider he goes. Of Giles’ last 15 pitches, 11 are sliders. Shin-Soo Choo, Ian Desmond, and Profar all go down swinging. Giles doesn’t have the cleanest outing, but it’s utterly dominant. About that slider. Giles was in complete control of it:

When our own Corinne Landrey looked at the resurgence of Giles last month, she found that early on in the season, Giles had been hanging too many of his sliders, and not burying enough. He’d lost the feel for his out pitch. That image above? That’s what feel for your out pitch looks like. Giles’ slider was unhittable, and he went to it more than he had all year. And that’s just an extension of a recent trend:

More than ever before in his career, Giles has lately been leaning on his slider. Perhaps that goes hand-in-hand with this:

Coinciding with a 10-game career high in slider usage is a 10-game career high in strikeout rate. The feel for Giles’ out pitch is back. His velocity is back. Over the last three months, a stretch spanning 32.2 innings and 136 batters faced, Giles has a 1.65 ERA, a 1.29 FIP, a 39% strikeout rate and exactly one home run allowed. At first glance, those numbers might look unsustainable, until you realize they’re not far off from what he did for consecutive seasons in Philadelphia. For three months, Giles has been the guy the Astros gave up Vincent Velasquez for. Giles is back to looking like one of baseball’s very most dominant relievers, and he’s back to pitching the ninth.

On Sunday, Ken Giles was so good, he actually made things harder on himself. Given where he was in April, it’s not the worst problem to have.