Daniel Norris, Justin Verlander, and the Tiger Slider

Don’t ask Justin Verlander if his new harder slider is a cutter, apparently. “Verlander is steadfast on this — he’s not throwing a cutter. It’s a slider,” is how Chris McCosky characterized the ace’s opinion on the changing pitch.

The difference between a cutter and a slider is difficult to really nail down — and is most easily represented as existing on a spectrum. First, there’s the cut fastball, thrown with a slightly offset grip but still a fastball release. That pitch usually goes about a mile or two slower than the four-seam with only a couple inches of drop beyond the four-seam. Mariano Rivera threw that thing better than anyone, but Adam Ottavino modeled it for us.

Then there’s the baby slider, a cutter grip thrown with a little more supination before release, and those go 4-plus mph slower and have a few inches more drop. Those are the pitches you see from Madison Bumgarner, Cole Hamels, Jon Lester, James Shields, and Adam Wainwright. Most of those pitchers refer to that pitch as a cutter, but most of those pitches also drop more than the overall average for the cutter.

To make matters worse, there’s a brand of slider thrown by the Mets which might fit between the “baby slider” cutter and the slider-slider. We’ve dubbed that pitch the Warthen Slider. And it might be the answer to why Verlander is throwing a harder slider that looks like a cutter, but one to which he still refers as a slider. And it might be part of the answer to why tonight’s starter Daniel Norris has seen such an improvement in his walk rate.

Let’s return to that piece about the Warthen Slider to get a definition from the Mets’ pitching coach himself. “It’s a different spin, it’s a different grip,” is how the coach characterizes it. “The whole idea is not to use your wrist to try and spin the ball. You want your fingers to spin the ball. You’re thinking fastball and just kind of cutting through the ball.” If you’re looking for an example of the offering, consider basically anyone on the Mets pitching staff. Noah Syndergaard, Matt Harvey, Jacob deGrom, Jeurys Familia, Hansel Robles, Robert Gsellman, and Seth Lugo all throw it.

If we were to use numbers to describe the pitch, we could use those pitchers as a starting point, and say the following about the Warthen Slider:

• It’s hard for a slider and soft for a cutter, about 4 mph slower than the fastball.
• It has more drop than a cutter and not as much drop as the better sliders.
• It’s a low-spin, high velocity slider, due to the mechanics.

So we can apply that rubric to the Tigers’ two fairly easily. Have their sliders gotten harder, retained more drop than the average cutter, and also lost some spin as the year has developed? In order to adjust for the fact that spin usually goes up with velocity, let’s reflect spin here as rpm per mph. Let’s also define velocity and drop against their fastball, since the fastball sets the tone.

Maybe these aren’t quite Warthen Sliders because the spin has actually increased. If you express it as a raw unit or a unit per mile per hour, the spin on both Norris’ and Verlander’s new sliders has gone up a bit.

But it should also be immediately clear that calling these cutters is a bit unfair. Both go more than 5 mph slower than their fastballs, and the average cutter is usually at least a mile per hour closer to the fastball. The drop is where these pitches really separate themselves — these guys have the drop differential almost always associated with a slider. Only two of the 77 pitchers who have thrown a cutter and a four-seam 100-plus times this year have a bigger drop differential than Norris, and only 15 have a bigger differnetial than Verlander.

One thing for which cutters are known more than sliders is command. They’re thrown in the zone close to 53% of the time, while sliders are thrown in the zone 49% of the time — and there are fewer balls to called strikes in the cutter grouping than the slider grouping. Norris’ slider was a ball 50% of the time last year; it’s been a ball only 32% of the time this year. That’s huge for a guy who has had issues with walks. Verlander’s change has been a little bit less drastic, but in the right direction. This new slider gets more swings in both cases.

So it’s the best of both worlds. This new pitch has the drop and velocity gap (and whiffs!) associated with a slider, but the command outcomes associated with a cutter. You can call it a hard slider, a Tiger slider, a proto-cutter, call it what you will. It’s working.