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Between the Numbers – Casey Mize

Imagine you’re a kid and it’s Christmas time. Under the tree is a beautifully wrapped gift with a cherry red bow and your name on the tag. To your surprise, on Christmas eve, you’re given the chance to open this gift and your heart skips a beat. You rush to the tree, rip it open, and there is a brand-new pair of pajamas, (one size too big at that). This is my metaphor for a dynasty leaguer’s experience with Casey Mize this year.

Casey Mize was drafted first overall by the Tigers in the 2018 first-year player draft. He dominated the lower minors right away and was promoted to Double-A early in 2019, showing impressive command and presence in 15 starts. The future was certainly bright for Mize and was ranked accordingly high on prospect lists all over the interwebs.

Of course, there was no minor league season in 2020, so our only looks at him this year are in the big leagues. Many thought he would succeed right away, and he was considered a must-add in roto leagues, but that has not been the case. Through his first five major league starts, Mize has thrown 20 innings, with 21 strikeouts but also 8 walks, a 5.85 ERA, and a 1.40 WHIP. The results present the question “what went wrong?”


Mize throws five pitches according to Statcast: a four-seamer (26.9% of the time), a sinker (22.4%), a split-finger (21.1%), a slider (18.9%), and a curve (10.7%). Not only are five-pitch arsenals rare in today’s game, but throwing each pitch with such regularity is very impressive. Many starting pitchers today will throw two pitches and flash a third, but you won’t find pitchers throwing five pitches with such regularity every day. Coming up through the minors, his split-finger and cutter were thought to be his best pitches, but all were considered potentially plus-or-better offerings.

The four-seam fastball measures in at 93.6 MPH on average, which is good, but not elite, in today’s game. There are currently eighty pitchers throwing the ball 95 MPH or harder, at a minimum of 250 fastballs. Obviously, there’s nothing to say that elite velocity will breed success and vice versa, but we should highlight that Mize’s fastball is not elite. Fellow number one overall pick Gerrit Cole’s fastball sits at 96.6 MPH, which is only good for 10th in baseball (min 500 fastballs). Despite both being top picks, it’s important to note “blowing it by ‘em” is not Casey Mize’s game.

The sinker plays well off of his fastball, as they both travel within 0.1 MPH of each other, but the sinker is only getting 10.3 Wiff%, meaning it is being put in play quite a bit. This is quite normal for sinkerball pitchers, but so far Casey is leaving it up about belt high regularly and he might benefit from keeping this pitch down a bit.

So far the positive scouting reports on the split-finger (88.3 MPH) are holding true, with a .240 xWOBA and an EV of 84.8, but he features it mostly to left-handed hitters and uses his slider (88.7 MPH) more against right-handed hitters. His slider, which was supposed to be a plus pitch, hasn’t been so far. With an xSLG of .583, xWOBA of .406, and EV of 88.2, it’s failed to fool many major league bats.

The least thrown pitch is his curve, and he uses it to both left and right-handed batters equally. The velocity on the pitch is only 80.6 MPH so it offers a nice contrast to the other four pitches that live between 85 and 95 MPH.


The stuff, while not great, suggests better results are attainable. A 10.9 SwStr% can be successful and if we look back into the minors he averaged closer to a 14 SwStr%, so there’s a hint to improvement there. Batters are swinging at 32.8% of the balls out of the zone, which is quite good.  That rate ranks 65th in baseball (Min 20 innings, so it includes relievers), and batters are only making contact with 64.9% of those swings. When we look at pitches in the zone, again a successful contact rate of 86.1%. This is some data to back up there is a hint of bad luck so far- Mize’s FIP (4.86) is nearly a full run better than his current ERA (5.85), and his SIERRA is an even better 4.54.

As far as movement goes, Mize gets great movement on his sinker and splitter, but his slider sits pretty flat and might be looking more like a slow cutter up in the zone to the batter. The four-seamer is close to league average as far as drop goes but does break away from left-handed hitters nicely. Here is a chart of all 5 pitches’ movement, Red is good compared to league average, Blue is bad

The sinker has great movement (see above) and good results (.313 SLG, .293 WOBA), but Statcast suggests there may be some luck involved (.569 xSLG, .432 xWOBA). This could be from the 88.9 EV and an unsustainable launch angle of 1.

The curve is perplexing, with a 41.7 Wiff%, and only put in play twice out of 40 curves thrown. The SLG % on these two batted ball events is 1.500 with an EV of 102.0. So, when the curve has been put in play, it has been hammered. Maybe this is a result of a small sample size, but the data we have shows he has left it up in the heart of the zone more than a couple of times, so that trend could continue.

The problem here overall is the stuff is still getting hit hard. Mize has the 17th highest Barrels per Batted Ball Event of 11.9% (Min 50 BBE) in baseball and a hard-hit rate of 42.4%. The spin on his fastball is 32nd percentile, and his curve is 20th which is not something to be excited about. This is not to say Mize can’t be successful, it suggests Mize needs to learn to play closer to the shadows of the strike zone and keep his breaking balls ball away from the heart of the plate.


The control for Mize was supposed to be a major plus for him coming up through the minors, walking only 5.4% of the batters he faced. With the Tigers, that walk rate has ballooned to 8.7% and plunked 4 more. A big contributor to this is he’s only thrown 37.3% of his pitches in the strike zone. There are guys like Aaron Nola and Blake Snell who have success throwing the ball out of the zone this much, but you need to throw more first-pitch strikes (to work ahead in the count) and have more swings out of the zone later in the at-bat.

The four hit-batters and walk rate are big red flags here, but maybe there are some early career jitters. In the minors, he only hit 9 guys in 123 innings, now 4 in 20. This is a clear sign Mize is not commanding his pitches, and he can’t afford to have balls sail in the big leagues, especially if he’s pitching behind in the count.

Here’s a graph of Mize’s placement by pitch. Maybe it’s only a small sample, but I have to admit I thought we’d see more consistent groupings. The split-finger pitch seems to be all over the place, and the four-seamer seems to be sailing on him regularly. It looks like he’s targeting two areas with his slider, but there’s not a ton of consistency there and one looks like he’s regularly trying to drop it in the top of the zone.

In reviewing his zone data, 58% of Mize’s walks have come from the last pitch being above the middle of the zone, either off the plate or above it completely. For a pitcher with four pitches that drop, you hate to see the payoff pitch be at the batter’s eye level or off the plate. As far as swinging strikes, he’s getting 55.5% of his Wiffs in the bottom third of the zone, or below. It’s going to be important to get more of his pitches that sailed high to be consistently at least near the top of the zone even if they’re still balls.

Game Trends

In his first four starts this season, Mize terrified Tigers fans and dynasty owners with a 6.75 ERA in 14.2 innings. He managed sixteen strikeouts but also six walks, a 1.71 WHIP while allowing three home runs. He had a 43.75% hard-hit rate and threw 58.8% of his first pitches for strikes.

His last start was much more successful, on the road against a tough White Sox team. This game he pitched 5.1 innings but only allowed one hit, and two walks while striking out five and allowing two runs (one coming after he left the game). The underlying stat I want to highlight is he threw 77.8% of his pitches for strikes. Of those first-pitch strikes included three fastballs, seven sinkers, two curveballs, and a slider, all in the zone. Of these 18 pitches, only 4 I’d categorize as hitting the heart of the zone, and none resulting in a hit.

It’s going to be very important for him to repeat this, and command all of his pitches towards the outer edges of the strike zone, setting up breaking balls to fall below it later in the count. He did throw five pitches out of the zone (fastballs and sliders), but that’s a low ratio and keeps the hitters guessing. He did result in one swing and miss out of the zone too.

The results in the rest of the notable advanced stats for this game fell in line beautifully. Exit velocity was a career-low 88.4, his FIP was 2.45, and the game score 67. The hard-hit rate for the game was 36% and only one ball was barrelled. The increase in first-pitch strikes, as well as improved zone placement, really stood out to me in this performance.

Keys to success

I still believe Casey Mize can succeed with the skills he has, but we should not compare him to Gerrit Cole, despite sharing the honor of being chosen first overall. There is another pitcher with five pitches and similar velocity levels having great success today named Shane Bieber. I’d like to see Mize mimic Bieber’s game more, spotting his fastball anywhere above the knees, in and out of the zone. Using his sinker and slider to live on the shadows of the strike zone more, specifically the corners, allowing his split and curve to be chase pitches to put hitters away.

To do this though, Casey will need to improve spin on his fastball, likely adding strength to his fingers in his pitching hand or adjusting his grip (which could also help the movement). He’ll also, and maybe more importantly, need to regain the control and consistency he showed in the minors. These two things will allow him to increase his first pitch strike ratio previously mentioned and work ahead in the count more. It is vitally important for a pitcher who uses deception and control to work ahead in the count. If not, the batter can lay off pitches they don’t pick up out of his hand and force the pitcher into the heart of the plate. Mize has shown he can do this, but now he must be more consistent about it.

The Author

Ken Balderston

Ken Balderston

20+ years of fantasy baseball experience & currently only playing in dynasty leagues. Christian, proud father of 3, husband to the strongest woman in the world, accountant, golfer, cook.

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