You might not have noticed, but the Houston Astros have a type — relief pitchers who can get batters to swing and miss at pitches. That sounds simple, because it is. Every team wants their bullpen stocked with swing-and-miss pitchers! Even if you have the best defense on the planet, nothing can beat the nice breeze sent toward the mound after a whiff. It is, as they say, the good stuff.

It is the stuff that the Houston Astros have done at an extraordinary rate in 2017. As a bullpen, the Astros have the highest swinging-strike rate (14.9 percent) since recording of that type of thing began. To this point in the season, they also have the highest bullpen strikeout rate (31.1 percent) in recorded history — and by a healthy margin. If you consider the MLB average strikeout rate for relievers, 23.2 percent, only one Astros reliever currently in the bullpen doesn’t reach this mark — Tony Sipp.

This isn’t surprising. Whiffs breed strikeouts, that part makes sense. The more you miss bats, the more likely you will be able to do it with two strikes. But consider this: That bullpen strikeout rate record they are currently beating? It is their own, a mark they set last season. They have been able to do this for two consecutive seasons, which sticks out to me as something that might allude to a larger trend. What have the Astros discovered in their bullpen that others have not? Let’s get a whiff of those, uh, whiffs — and their plate discipline data in general.

As you would expect of a team setting the record in cool breezes of air, the Astros bullpen is great at limiting contact. Its 70.3 percent mark last season and 67.5 percent mark this season represent the two lowest bullpen contact rates ever measured in professional baseball. But, like I said, you knew that. Whiffs = less contact. Whiffs are good. What stands out here is the remarkable rate at which Astros relievers have gotten hitters to whiff on pitches outside the strike zone this year:

Oh yeah, and over that span the Astros lead the majors in getting swings on pitches outside the strike zone (33.4 percent). The Astros this season have gotten swings outside the strike zone at a lower rate than last, but they have countered that by drawing even smaller amounts of contact. One thing is for certain: This is odd. For a team to excel at getting cuts that come up empty on pitches outside the zone as much as the Astros have, it points to something.

If you recall some work done by Eno Sarris, and another article written by Harry Pavlidis, sliders generate more swings and misses than any other pitch. The reason I brought that up is, well, the Astros are throwing a massive amount of sliders, and an absurdly low amount of fastballs. And it isn’t just happening in a vacuum — this has been something they have done more and more each year:

The MLB average usage rate for pitchers to this point in the season is 57 percent. Looking at Houston’s relievers who have thrown more than 10 innings this season and aren’t now a starter (looking at you, Brad Peacock), only one pitcher obtains a fastball usage rate over that mark — Michael Feliz (72.4 percent). Even Ken Giles, who joins Feliz in being the only other Astros reliever with above-MLB average heat, has devoted a higher percentage of his pitch usage to sliders than fastballs.

MLB-wide fastball usage for bullpens has fallen every year since 2012, despite a surge of pitch velocity in recent years. You would think hitters would struggle against higher velocity; however, Russell Carelton described a couple weeks ago why that might not be the case:

Consider the lament that started 10 years ago. Baseball was being over-run by pitchers, relievers especially, who threw really fast fastballs. Well, if you know that a lot of the pitchers whom you will be facing are going to be throwing heat, you might as well sit on the heat. You’re probably also going to be brought to the majors more quickly if you show some ability to hit that heat. This is not rocket science.

Russell is right. It isn’t rocket science! High velocity is abundant at nearly every level of the modern game. That isn’t to say it is useless, but the fact that it has (as Russell points out) been true for around a decade means hitters have had an apt amount of time to adjust. More abundant high-velocity pitchers at various levels of development — professional or otherwise — have also helped to normalize velocity alone.

That isn’t to say that fastballs are easier to hit. What it does appear to mean is that fastballs/hard pitches — particularly those with less movement — are not only what hitters are looking for, it appears to be what they are stubbornly sitting on. They feel more confident hitting a fastball than a wicked slider, changeup, curveball, etc., so that is what they will wait for.

George Springer will not be cheated The Astros center fielder leaves it all at the plate.

How do you counteract this? Throw more often a pitch the hitter does not want to hit. The Astros have figured this out. It isn’t a pitcher abandoning their fastball altogether, but it is a trend toward limiting the amount of fastballs a hitter sees each at-bat. I mentioned sliders getting a ton of whiffs earlier, but they aren’t the only offering coming from the relievers in the ‘Stros bullpen; Chris Devenski makes his money on that nice changeup. Clearly the overall theme here is less fastballs, more offspeed.

One problem you might think with this strategy is that you run the risk of walking a lot more people, as offspeed pitches can’t be thrown for strikes all the time. As I mentioned before, Astro relievers have gotten people to chase outside the strike zone five percent less than last season, which is partially to blame for an elevated walk rate (9.6 percent). If you live by getting people to chase outside the strike zone, you run the risk of dying by hitters not swinging. But…is that really a death at all?

In Carleton’s article, he also describes how hitters don’t care about striking out as much in modern baseball. This is because a strikeout is just one out. He mentions that with two outs or no one on, a strikeout is the same as any other out. And the argument that “balls in play move runners over” isn’t as true as you would think, because it works out that way only about 20 percent of the time. By striking out, hitters avoid double plays and don’t sacrifice power for contact.

We can apply that same reasoning to walks for pitchers, which function generally the same way. A free pass is the exact same thing as a single. The difference? By issuing ball four instead, pitchers don’t run the risk of surrendering extra-base hits or their defense making an error that moves the runner up. At the same time, consider the difference between a single with a runner on second base and a walk with a runner on second. The former will likely get the runner home, while the latter just cycles in another batter and sends to old one to first base.

There are plenty of other examples like this, but let’s consider what walks are at their heart — pitches outside the strike zone. With the assumption that offspeed pitches garner more swings outside the zone than fastballs, and more swings and misses overall, Astro relievers aren’t afraid to tempt hitters into chasing their excellent non-fastballs out of the zone. Eno Sarris talked about this subject in a piece he wrote earlier this month at FanGraphs. His premise was a question about what it would look like to see a pitcher whose usage consists of 80 percent offspeed stuff, and in the article he said this:

The average breaking pitch doesn’t land in the zone as much as the average fastball, no. But if you had a pitcher with multiple distinct breaking balls — and good command of those pitches — you might want to consider pushing that breaking-ball percentage as high as it can go, right?

That is exactly it, and what the Astros have done since the start of 2016. Consider current/former Houston relievers Peacock, Sipp, Kevin Chapman, or Pat Neshek. All saw or have seen dips in fastball usage post-2015, during their time spent in Houston, and a surge in slider usage. Look at Feliz, even though he has become essentially a 70/30 FB/SL usage guy. His slider is ridiculous, and I’ve written before about how often it generates whiffs. Giles is another fitting example of the new Astros philosophy, as he has become a majority-slider pitcher since his trade over from the Philadelphia Phillies just before the 2016 season. Despite his struggles this year, you can even toss in Luke Gregerson, who has always been a non-fastball heavy pitcher.

All those are good, but no better example of this ‘non-fastball’ philosophy comes to mind, however, than James Hoyt. He was, of course, part of the Evan Gattis deal in 2015. Hoyt, a former pitcher for a Division 3 school in Louisiana, was not a prospect. Grant Brisbee did a good profile on him, but he was essentially just a guy that struck out the world in the minor leagues.

Now, there isn’t really a way to tell if Hoyt threw his devastating slider as much in his time spent on the farm pre-Astros. What we do know is that it skyrocketed in Triple A in 2016 to around 44 percent, a rate about 10 percentage points higher than he ever had. Like I said, we’ll never know if his usage changed, but what we do know is that he is the prototypical pitcher for what the Astros are trying to do. His usage is about 40/60 in favor of offspeed pitches, with the overwhelming majority being sliders. He also owns an incredible 21.4 whiff rate on pitches outside the strike zone — an area where he sits most of the time and entices a swing at a rate well over the MLB average.

In one way, the Astros bullpen is a microcosm of a trend we’re seeing among all relievers. Fastballs are on the decline, and sliders are on the rise. Moving pitchers to the bullpen allows teams to highlight the best that pitcher has to offer. They can throw their best pitch a ton, as they can consolidate down to two or three offerings total and don’t have to worry about pitching to contact to avoid working up a high pitch count.

On the other hand, the Astros are taking it a step further. The effort they have made these past two seasons far surpasses the trend of MLB. From the outside, it appears that they are telling their relievers that it’s fine to pitch backward. That throwing fewer fastballs and more breaking pitches runs counter to what a lot of hitters are looking for today, and might be one of the reasons why their bullpen has one of the lowest swing-rates inside the strike zone in the majors. That walks aren’t that bad, especially for relievers, because if you stay close yet outside the strike zone you run less of a risk to give up hit and still maintain a strikeout potency. And that if you stick to attempting to get swings outside the strike zone, it is harder for hitters to get the extra base hits that would make you pay for all those walks, anyway. This isn’t relievers being wild and getting lucky. What we’re seeing is pitchers commanding their offspeed pitches while also not being afraid to pitch outside the strike zone, not fearing walks for the sake of contact. In a way, they’re being effectively wild.

Although, to this point, I’ve highlighted why the Astros might be trying to stray from enticing contact, that doesn’t mean they’ve done a poor job at limiting the damage done by it. I should point out that one in every four balls put in play this year has been what is considered soft contact, as measured by BIS. That’s the highest rate since 2011. Mike Petriello wrote a fantastic article the other day about this exact thing, and he really highlights how the Astros are even combining an incredible ability to miss bats with an ability to create weak contact.

The Astros are onto something here — the realization that pitchers don’t have to trade weak contact for whiffs. It’s much like the hitting revolution we have seen in recent years; hitters have noticed that power and contact can coexist, and pitchers have seen the same for whiffs and soft contact. For starting pitchers, the unfavorable factor into this is that you run the risk of a higher pitch count earlier in games. That is the reason, at least in my mind, that this works so well as a tactic for relief pitchers, who are less concerned about pitch counts.

With as much success as the Astros have had at keeping a consistently strong bullpen since (seemingly) employing this ‘non-fastball’ initiative in 2016, this could be something we see gain even more steam around the majors this offseason than we are now. Will it? Who knows. About all I know is that the Astros bullpen contains some of the most interesting pitches and intriguing pitchers in baseball, and its design appears to be well ahead of the curve.

BIS data from FanGraphs used for pitch types

All data as of Saturday, May 27

Shawn Brody is a contributor for Beyond the Box Score, producer of In Play, Pod(cast), and a pitcher recovering from Tommy John at Howard Payne University. He is a Junior double majoring in Business Management and Computer Information Systems. You can follow him on Twitter @ShawnBrody or email him at Shawnbrody9@gmail.com