The 2020 Tampa Bay Rays arguably have one of the best front-end starting rotations in the American League, with Charlie Morton, Blake Snell, and Tyler Glasnow as the headliners. Last season, Glasnow flashed moments of brilliance prior to and following a mid-season injury that halted his torrid start in early May and kept him out of the rotation until September. Glasnow already has the ability to be the ace of the Rays staff — in his 60.2 innings, the right-hander was worth 2.3 WAR and posted a 1.78 ERA and 2.26 FIP — but a couple of minor adjustments could vault him into 2020 Cy Young Award discussions.

Glasnow, who avoided salary arbitration last Friday by agreeing to a one-year, $2.05 million deal, operates with three pitches: a straight, backspinning four-seam fastball that has some carry and can sometimes have cutting action; a 12-6 diving curveball; and a hard changeup that exceeds 90 mph.

Let’s start by looking at Glasnow’s four-seamer, one of the straightest in baseball with a good amount of rise:

Back in late April 2019, David Laurila discussed Glasnow’s fastball with him, including how he creates two slight variations, a back-spinner and cutter:

I’m a power pitcher. My emphasis is on velo, spin rate, spin efficiency, carry — just efficiency of the fastball in general. I have a different fastball grip. My fingers are curved, and I cut the ball. I’ve always had a pretty wide grip on my fastball, and that’s kind of been the reason I cut it.

Glasnow’s curveball, the movement of which juxtaposes with the movement profile of his four-seamer, has almost perfect topspin that drops counteractively to the fastball, albeit with some slight sweep depending on where he wants to locate it:

As for his changeup, Glasnow threw something in the neighborhood of 30 in 2019. Thrown much harder than the league average, it produces decent arm-side run and drops less than other changeups. The latter attribute is due to Glasnow inducing more backspin than sidespin under a 2:00 spin direction:

Back in mid-May, Glasnow went down with forearm soreness, which eventually landed him on the 60-day injured list. He didn’t return to the rotation until September; a setback during his rehab in June pushed his return date later than he’d hoped. Upon his return, Glasnow became strictly a two-pitch pitcher, using just his four-seamer and curveball. There were other changes as well — mainly how hard Glasnow was throwing his four-seamer and the amount of spin he was creating. Glasnow’s fastball went from an average velocity of about 97 mph to 98 mph, and his spin rate jumped from 2219 rpm from March to May to 2348 rpm during his four starts in September.

Here’s a look at how that increase in both velocity and spin affected his four-seamer’s pitch shape:

With that extra mile per hour and 100-plus additional revolutions, Glasnow got something in the neighborhood of an extra inch of rise. That additional lift might not seem like much, but it can be the difference between a fly ball and a whiff, the latter of which Glasnow was still getting about once in every four swings.

These improvements to Glasnow’s four-seamer helped his curveball, which otherwise stayed largely the same throughout the season. The difference in performance was clear, as evidenced by using Alex Chamberlain’s Pitch Leaderboard tool, which shows that the whiff rate on Glasnow’s curveball went from around 35% to over 55%.

Extra movement (or lack of vertical break) on the four-seamer induces a larger plate spread for the hitter once both pitches breach the tunnel point. Have a look at Glasnow’s four-seamer and curveball tunnel metrics for 2019.

Tyler Glasnow 2019 FB/CB Tunnel Metrics Sequence Side Count RelDist PreMax PlatePreRatio CU|FA L 19 1.90 1.28 13.2 CU|FA R 30 1.80 1.44 18.3 FA|CU L 24 1.59 1.33 17.9 FA|CU R 45 1.67 1.48 13.5 SOURCE: Baseball Prospectus

All of the figures above are better than average for Glasnow. His release points look the closest to lefties when going fastball to curve. The tightest tunnel occurs to lefties as well, but when Glasnow leads with the curve, he creates the largest tunnel point to plate location ratio to righties going curve to four-seam.

Not only can Glasnow tunnel his two main pitches better than most pitchers, the design on both pitches also allows him to create spin mirroring that approaches near perfection – an exact repelling 180-degree spin with a minor disparity in terms of gyro degree. Have a look at the action under his average 2019 metrics using the Driveline Edge tool:

The spin mirroring is exemplified by how much of a vertical contrast is present when the fastball and curveball reach the plate. This is due to the opposing effect that Magnus Force creates on both: the upwards momentum on the fastball, and the downward pull on the curveball, which creates the upward movement.

With all of that said, you might think Glasnow could just keep going with his two-pitch approach. Perhaps if the Rays decide to regulate him to an Opener role (which he sort of was when he came back in September), that could work. However, there aren’t many starting pitchers who have been successful long-term taking a two-pitch approach, and the Rays surely want to reap the benefits of Glasnow in the rotation.

Case in point: during the Rays’ 2019 post-season, Glasnow made two starts against the Houston Astros. He pitched 4.1 innings on October 4 and gave up two earned runs off four hits and three walks while striking out five hitters. He followed with a dismal 2.2 inning showing on October 10, when he was shelled by four runs off five hits.

Despite all the stated advantages Glasnow enjoys with his four-seamer and curveball, he should include his changeup much more often. He doesn’t need an additional swing-and-miss pitch, but one that can induce weak contact by timing disruption. This isn’t to say that there is a problem with the pitch as it is now. Rather, its action could be improved to make it a dynamic addition to his mirrored four-seam and curveball.

Glasnow, along with the likes of Dinelson Lamet, Jeurys Familia, and Walker Buehler, threw his change much harder than others who use the pitch regularly. With its high velocity and low spin rate (1774 rpm), Glasnow almost created a hard-running, slower version of his fastball with more rise than drop.

What I’d like to see from Glasnow is an adjustment to both the velocity and spin direction of his changeup. If he can bring that direction closer to 3:00 than where he’s been throwing it (2:00), we would be looking at a 90-degree spin tilt difference off both his four-seamer and curveball. Then, hitters would have to worry about how difficult it will be to split the difference between the fastball and curve, and also have to contend with a third pitch breaking off horizontally from the other two.

First, let’s look at his normal changeup against the suggestion I’ve made. I took off 4 mph and dropped the spin rate 10 rpms for each mph reduced. I also made a small adjustment to the spin efficiency, because the adjustment to the spin direction might lend itself to a changed gyro degree as well:

Clearly, the suggested version not only creates more arm-side run but a little more drop as well. It will take a bit of work to make these changes, especially for a self-proclaimed power pitcher who thrives on velocity, but it’s not impossible.

Another step in redesigning the changeup is an arm-slot change to help add more sidespin. Right now, as we saw in the earlier three-pitch overlay, Glasnow already has some separation from his four-seamer and curve:

Since Glasnow tends to create backspin on his changeup, given his arm slot when doing so, you’d expect he’d need to lower his release point an inch or two in order to help facilitate the adjustment to the changeup. On the other hand, if Glasnow were to maintain his current changeup release point, it would involve a wrist and/or post-release pronation adjustment.

Here’s a demonstration of what Glasnow’s 2020 arsenal would look like, again using the Driveline Edge tool:

Glasnow throws hard and gets good movement on his fastball, strong action off his curveball, and has a changeup that could use some tweaking to better match with them. The tunneling action doesn’t have to be ideal; hitters knowing they have to account for the repelling action and hard-to-distinguish spin direction will then be tasked with making good cuts on a changeup that can slide away from a lefty or break in on the hands of a righty.

It’s not likely that Glasnow returns to the mound in 2020 armed with just two pitches, as great as they might be. Having a more prominent third option — and designing it to work off his other pitches — could not only earn Glasnow the title of staff ace, but a league ace as well.