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Who Throws the Nastiest Fastball in MLB?

Baseball has never had a greater abundance of filthy fastballs than it does right now. But which pitcher or pitchers have the most disgusting heaters in MLB? And how exactly does one determine a fastball's nastiness?

When it comes to judging nastiness of a pitch, there’s really only one set of criteria: you know it when you see it, Justice Potter Stewart-style. But nasty comes in different forms, manifested in different ways. It can be the velo, the movement, the overall style. A universal accounting of nastiness has a lot to incorporate, in other words. So as the season slides into summer, we’re on a quest for the nastiest pitches in baseball right now—appreciating all the many ways to be nasty, looking for the pitches at the top of each category. (This part is easier than ever with Statcast’s new pitch arsenal and movement leaderboards.) It might be impossible to identify a single final answer. But we can pick out the finalists, building a broad catalogue of filth.  

We’ll be going pitch type by pitch type, beginning today with the fastball. But is the nastiest fastball just the fastest one? Or the cutter with the best cut? What about the sinker with the most sink? Something else?

The Hardest One

This one is the easiest. It’s direct—triple-digit radar reads get a gasp from everyone, regardless of context. It might as well have cartoon flames trailing behind it. It sounds different. And there’s no question about where it’s coming from: Jordan Hicks.

The Cardinals reliever has not only the highest average velocity of any pitcher this season, not only the fastest individual pitch on record in 2019, but the eighteen fastest pitches. This leaderboard doesn’t look like a leaderboard so much as it looks like the result of someone being punished with writing the same name over and over and over. Hicks threw baseball’s hardest pitch (104.2 mph) through its 18th hardest (102.7 mph), and its 20th hardest (102.6 mph) through its 71st hardest (101.7). Yep: Take the 71 fastest pitches in MLB in 2019, and 70 belong to Hicks. (The 19th hardest pitch belongs to Tayron Guerrero of the Marlins.)

Remember Aroldis Chapman? You know, the guy who threw 105 mph before? His fastest pitch this year ranks 113th on this list—and he still threw it 101.3 mph.

Hicks has thrown nearly half (47%) of his pitches at or above 100 mph. The next highest rate comes from Guerrero, who's only thrown 16% of his pitches at triple digits.

Hicks dominates the heater like no other. It’s the most straightforward type of nasty—but this doesn’t make it any less impressive.

The One With The Highest Whiff Rate

What about results, though? A blistering fastball is universally frightening, but velo is only one piece of the conversation. There can be just as much, if not more, nastiness in the reaction to a pitch, beyond the pitch itself—buckling knees, off-balance swings, dramatic tumbles. After all, what better testament is there to a pitch’s quality than a humiliated hitter? Maybe the truest measure of filth, then, is how difficult it is to handle. So which fastball results in the most whiffs?

How disgusting is Josh Hader’s fourseamer? Hitters swing and miss on 27.5% of them. That’s more than double the average, and close to triple. But you don’t get baseball’s highest overall strikeout rate—more than half of opposing batters!—without a number like this, or individual hitter reactions like these.

The Cutter With The Sharpest Break

But filth doesn’t have to register on the radar gun, and it doesn’t necessarily have to end in a K. A pitch’s clearest display of artistry can be in its movement, and when this artistry is extreme enough to border on witchcraft, there might not be anything nastier. Enter Roberto Osuna’s cutter—which deserves the name more than any other rendition of the pitch, cutting twice as much as a typical cutter. (Literally: Osuna’s breaks exactly 200% more than the league average.)

The Sinker With The Biggest Drop

On to the other big category of fastball movement—a sinker’s sink. It might not pack as much drama as a falling-off-a-table curve, but it brings even more intensity, and, anyway, this is the fastball section. There’s no competition here: Jared Hughes’s sinker sinks more than anyone else’s (49% more than the average), which translates to nearly an extra foot of total drop.

The One With The Lowest Batting Average

Maybe nasty doesn’t have to be about any of the above, though—not flashing radar guns or crazy whiffs or dramatic movement. Maybe the nastiest move of all is chilling efficiency, the pitch that simply allows the fewest hits. The fastball with the lowest batting average is… Josh Hader’s fourseamer (.110), which we’ve already seen here. But just a few decimal points behind that is Diego Castillo’s cutter, at .115, which is slider-y enough to be more of a slutter, but it’s classified as a cutter by Baseball Savant, which is good enough for us. Regardless, it’s nasty by any name:

The Eye Test

And then there are some that don’t need a space on any leaderboard. Like José Alvarado’s sinker…

…or Luis Castillo’s…

…or Gerrit Cole’s fourseamer.

Check back in the next couple weeks as we delve into baseball's best breaking and offspeed pitches.