If you have been a baseball fan for any length of time, chances are you have heard this saying before: Hitting a baseball is the hardest thing to do in sports.

There is some truth there. When I showed up at the batting cages for my first — and last — year of high school baseball, my coaches set the machine to 85 MPH. I did not make contact the entire evening, and if I had, I would have accepted no explanation other than an act of divine intervention.

Hitting is hard, but even baseball fans often forget: Throwing even a pedestrian major-league fastball might be harder, not to mention the plethora of other weapons every major-league pitch must have to get big-league hitters out.

As the legendary Pitching Ninja Twitter account has taught us, pitching is an art-form, and I am convinced you do not have to be a baseball fan to enjoy it. Zac Gallen’s fastball-curveball combo — the engine that has powered his historic run over the last two months — is objectively awesome.

You probably sense that Gallen’s fastball and curveball are two of the best pitches by any Diamondbacks pitcher. But are they the best? Who throws the best changeup? What about the best slider? And most importantly, how would you even tell?

Evaluating an individual pitch for a given pitcher is difficult. We can look at, say, batting average or whiff rate, but those stats fail to capture the whole story. After all, some of the most valuable pitches — like a 2-1 curveball that drops in for a called strike with the bases loaded — are not swung at to begin with, yet still carry significant value.

This is where run value lends a hand, a stat measured for specific pitches that is defined as “the run impact of an event based on the runners on base, outs, ball and strike count.” Essentially, it assigns a value to every pitch thrown throughout the season in terms of how many greater or fewer runs the opposition is expected to score as a result of that pitch. Added up over the course of the season, run value helps us identify which pitches are most and least effective.

Another factor to consider is usage rate. For a pitch to be truly valuable in and of itself, a pitcher must be able to use it frequently. If a pitch grades out well in run value but doesn’t see much use, we should tap the breaks on calling it an elite pitch.

Madison Bumgarner’s changeup, for example, grades out as one of the best on the team according to run value, but he only throws it about 11 percent of the time. Its effectiveness may be better explained by the fact that hitters don’t see it often than that it is actually one of the best changeups on the roster.

Now that we have some helpful evaluation tools at our disposal, let’s get to it. Here is the best of each pitch type on the Diamondbacks.

Four-seam fastball: Zac Gallen

Honorable Mentions: Drey Jameson, Ryne Nelson

Zac Gallen’s heater is more than the best four-seamer on the team. It has produced more run value — 17 runs above average, to be exact — than any pitch by any Diamondbacks pitcher. 

Why is it so effective? For starters, Gallen is throwing it harder than ever before, at an average of 94.1 MPH. In an era of flame-throwers, that is still slightly below league-average. For a starting pitcher, though, it is more than respectable.

On top of the increased velocity, Gallen’s average four-seamer spin rate sits at a career-high 2,420 RPM, which ranks in the 90th percentile. That gives Gallen’s four-seamer some extra carry, making it particularly effective up in the strike zone.

You can see it at work here against Dodgers’ outfielder Trayce Thompson. It just feels faster than 94 MPH.

Recent call-ups Ryne Nelson and Drey Jameson share the honorable mention here. In a very limited sample size, both Nelson and Jameson’s four-seamers have graded out even better than Gallen’s on a per-pitch basis. Jameson’s movement profile is close to average, but 98 MPH plays regardless.

Nelson’s heater has a tick or two less of velocity, but he more than makes up for it with impressive vertical ride, in similar fashion to Gallen. In a year or two, Nelson’s heater could be the best on the staff.

Having already given out two honorable mentions, I might as well give out a third. Merrill Kelly’s four-seamer has produced the fourth-most run value of any pitch on the team in 2022. It also has above-average spin and plays better up in the zone than you’d expect at 93 MPH.

The fact that the Diamondbacks pitching staff is seemingly overrun with high four-seamers is no coincidence after new pitching coach Brent Strom took over this offseason. Strom made it clear upon his arrival that he wanted to see more top-shelf heaters.

Sinker: Joe Mantiply

Honorable Mention: Drey Jameson

Based on run value, the best sinker on the Diamondbacks, by a fairly wide margin, belongs to 2022 All-Star reliever Joe Mantiply. With a usage rate of 41.1 percent, Mantiply’s sinker averages just 90 MPH but has exceptional movement, both horizontally and vertically.

It is not a swing-and-miss pitch — few sinkers are — but it is not meant to be. He throws it for strikes and gets loads of ground balls. When opposing hitters do make contact, it is almost certain to be an out or a single; Mantiply has allowed just one extra-base hit on the sinker all year.

Here, he gets Brandon Belt to ground out into the shift.

Once again, Jameson’s stuff is too nasty not to warrant a mention. A recent addition to his arsenal, Jameson’s sinker has averaged 95 MPH since joining the big leagues and has proven valuable for getting outs early in counts.

Having learned the grip from former Diamondback Matt Peacock, Jameson gets good downward movement and occasionally eye-popping horizontal sweep, as can be seen here.

Changeup: Zach Davies

Honorable mention: Caleb Smith

After grading out as one of the best pitches in baseball in 2020 and one of the worst in 2021, Zach Davies’ changeup is back near the top of the ranks in 2022. For the year, it has produced 12 runs above average, which is the fourth-most among all changeups in baseball, trailing only those of Sandy Alcántara, Tyler Anderson and Shane McClanahan.

Davies’ signature pitch is effective due to a combination of an impressive 32.4-percent whiff rate and a relatively low 25.6-percent hard-hit rate. It works against both lefties and righties, too.

The honorable mention here goes to left-handed reliever Caleb Smith. Out of 141 pitchers who have used a changeup in at least 50 plate appearances this season, Smith ranks 14th with a whiff rate of 41.8 percent on the pitch.

When opposing hitters do put Smith’s changeup in play, they don’t do much, with a batting average of .161 and a slugging percentage of .221 this season. It is a genuinely great pitch that deserves more attention than it gets.

Curveball: Zac Gallen

Honorable mention: Joe Mantiply

Based on run value, Gallen’s curveball trails only his fastball as the most valuable pitch by any Diamondbacks pitcher this season. The numbers are silly. In 139 plate appearances that have ended on a Gallen curveball, opposing hitters are batting .165 with a .256 slugging percentage.

Gallen’s curveball has always been a good pitch, one that has arguably been underused in the past. This year, he has made some tweaks, throwing it about 2 MPH harder than he did last year with similar vertical movement but less horizontal movement.

As shown with Pitching Ninja’s tweet above, Gallen’s curveball tunnels beautifully with his four-seam fastball. Both pitches start from the same release point. The heater, propelled by Gallen’s elite spin rate, appears to climb up to the top of the zone. The curveball, meanwhile, completely drops off the table.

Technically, no other D-backs curveballs grade out above-average based on run value, but Joe Mantiply’s at least warrants a mention.

With a usage rate of just over 30 percent, Mantiply’s curveball has one of the highest curve whiff rates in baseball at 44.9 percent. Opposing hitters are batting .227 with a .379 slugging percentage when they put it in play, and Baseball Savant’s expected stats suggest those numbers should be lower.

Here is an example of Mantiply’s curveball, as he gets a big strikeout of Justin Turner with the bases loaded.

Cutter: Merrill Kelly

Honorable mention: Zac Gallen

Merrill Kelly does not use his cutter often — just 17.7 percent of the time — but when he does, it is a very good pitch. This year, Kelly’s cutter has been worth seven runs above average, and opposing hitters are batting just .176 with a .320 slugging percentage against it.

Kelly’s cutter is a bit of an oddball (no pun intended) with significant vertical depth for its velocity but very little horizontal movement. At an average of 91 MPH, the cutter is just a tick slower than his fastball, and the two play off each other nicely.

Here, Kelly dots the lower outside-corner against Jason Vosler for a called third strike.

Gallen gets his name in here, too, with a cutter that features essentially opposite movement from Kelly’s. At an average speed of 90 MPH, Gallen’s cutter has below-average drop but elite horizontal movement.

Slider: Reyes Moronta

Honorable mention: Drey Jameson

The best slider on the D-backs is something of a toss-up. On a per-pitch basis, run value pegs Jameson, Reyes Moronta, Keynan Middleton and even mid-season send-down Sean Poppen as viable candidates. The eye test says Kevin Ginkel should be in the mix, too. Officially, I’ll give it to Moronta, who has thrown a significantly larger sample of sliders in the big leagues this year than most of the others.

In 46 plate appearances that have ended with a Moronta slider, opposing hitters are batting .146 with a .163 slugging percentage. Moronta has also generated plenty of swing-and-miss on the offering, with a whiff rate of 48.8 percent. 

Here is a particularly nasty one that sent Wilmer Flores back to the dugout.

The sample size on Jameson’s slider is very small, but the results have been spectacular. Not only has he shown the ability to throw the pitch in the zone for strikes, but his 52.8 percent whiff rate is eye-popping.

With Jameson’s name showing up all over the place in this piece, it is easy to see why Strom said this about him over the weekend: “He’s got everything that is needed to be a frontline starting pitcher for a first-division team.”

The future of the Diamondbacks’ starting rotation is brighter than it has been in a long time.

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Top photo: Allan Henry/USA TODAY Sports