top of page

A Six Start Check In On Steven Matz

Hello! My name is Ben Cerutti. It's been a while, so I figured I might re-introduce myself to this blogging community.

I am coming at you today with an in depth look at what left-handed starting pitcher Steven Matz, the Cardinals biggest ticket acquisition of the 2021-22 offseason, has done through 6 games as a Cardinal. Obviously, the pick up was one that I did not like at the time. He has not done a lot to change my opinion of him as a pitcher (because I obviously don't know him as a person - although from all accounts I can find online he seems to be a genuinely good person and for that I applaud him) and because of that I was hesitant to write anything about him until I saw a couple of tweets that made me want to look deeper into some things about this southpaw hurler.

As it sits right now, Steven Matz has had three starts with the Cardinals that can be qualified as absolutely terrible and three starts with the Cardinals that range from good to great. Unfortunately, as it stands, the former has overshadowed the latter. Let's get the nitty gritty statistics out of the way, but before I do so, I must defer to people smarter than I who always add the early season caveats of: This is an extremely small sample size and we should go into this exercise knowing it! So...extremely small sample coming.

Steven Matz currently is sporting a 3-2 record with 25 2/3 innings pitched (less than 4 1/3 innings an outing) with a 7.01 ERA, 34 hits allowed, 8 walks allowed, 1 hit batter, and 30 strikeouts. That's good for about 4 hits every three innings, a WHIP of 1.636, and a K:BB of 3.75. The strikeout and K:BB numbers look nice but other than that it's pretty bad overall. Let's break it down into good and bad starts, though:

Good starts: 3-0, 16 2/3 IP (5.56 IP/start), 14 hits allowed, 1 HBP, 16:2 K:BB, a WHIP of 1.02, and just one run allowed (one earned) giving him an ERA of just 0.54 in those three starts. Those starts were at home against the Kansas City Royals, on the road against the Milwaukee Brewers, and on the road against the Cincinnati Reds. The Royals and the Reds are the bottom two teams in the league by OPS+ while the Brewers are slightly above league average at the time of this writing.

Bad starts: 0-2, 9 IP (3 IP/start), 20 hits allowed, 0 HBP, 14:6 K:BB, a WHIP of 2.89, and 19 runs allowed (all earned) giving him an ERA of 19.00 in those three starts. Those starts were at home against the New York Mets, at home against the Pittsburgh Pirates, and on the road against the San Francisco Giants. The Pirates are slightly below average by OPS+ and the Giants are slightly above average by OPS+ while the Mets are 5th best in the league by that measure at the time of this writing.

Let's get to the first of two tweets that set my mind a-racing.


The first tweet (above) that I want to look into talked about how Steven Matz in the past had been much better than average when his sinker (fastball) velocity sat at 95 and above in starts but when it sat 94 or below he typically got shelled. As velocity tends to decrease with age, this could definitely be seen as a bad sign moving forward. Looking just at Matz's 2020, 2021, and 2022 seasons as a guide, let's try to shake this out a bit.

With the above chart being Steven Matz's average pitch velocity by game for those three seasons, you can see that there is a general decline going on here, even if it is only but a slight one as the y-axis (vertical) is broken up into tiny 0.5 mph increments. I don't know that this stat matters so much in 2022 alone because honestly, he hasn't had a single game yet this year with an average fastball velocity of 95+ mph. If you look on that chart above, though, his "good" games of 2022 were the 2nd, 3rd, and 5th data points in the far right squiggle on the graph and his "bad" games were the 1st, 4th, and 6th data points on that same squiggle (professional terminology, obviously). Two of his three highest velocity games were his best and two of his three lowest velocity games were his worst. So there's that.

If we look at individual plate appearances ending in sinkers this year, the trend above doesn't really hold up - like, at all. On individual sinkers thrown 95 mph or faster this year, opposing batters have hit .500/.538/.750/1.288 with a 15.4% K rate and 7.7% BB rate on 13 plate appearances. On individual sinkers thrown 94 mph or slower this year, opposing batters have hit .316/.381/.737/1.118 with a 28.6% K rate and 9.5% BB rate. It's actually been flip flopped on his results - not that either have been particularly enticing.


The second tweet is a response to a tweet of mine that I wrote after reading Blake Newberry's piece on Steven Matz on May 10th. Notice what RC says below:

I don't need to post the stats by catcher because I already did above. Andrew Knizner has caught Steven Matz in literally all 3 wins and only those 3 games whereas Yadier Molina has caught Steven Matz in literally all 3 games in which he got crushed and only those 3 games.

However, I continued that conversation above with RC a bit there on Twitter, but decided to really look into something after that. I wanted to see what differences there were when Matz was throwing with Yadi behind the plate vs. throwing with Knizner behind the plate. There was one thing that really stood out to me immediately. Here is a graphic showing pitch types and locations first with Knizner behind the plate and then fading into pitch types and locations with Yadi behind the plate.

WOWIE! Anyone else notice something? Look at the yellow dots! If you're seeing the Knizner page, you think I'm absolutely crazy right now...because there ARE NO YELLOW DOTS. He hasn't thrown a single slider with Knizner behind the dish, but he's thrown 19 in three games with Yadi. Those have only ended 5 plate appearances (a BB, 2 singles, a ground out, and a K). So that's not the difference between how well he's pitched in games with Knizner behind the plate vs. Yadi, but it's what stood out to me immediately.

Maybe I do need to post some more stats about Matz's game with Yadi vs. Knizner behind the plate. Let's look to get a better idea of what's going on.

The first thing I want to look at is about halfway down the left side chart where it says % LHH faced and % RHH faced because I think that frames this next bit of conversation just a little. Matz has faced 30% LHH when Yadi's been behind the dish vs. only 15.5% of LHH when Knizner's been behind the plate. In Matz's career, he's been about equally good against LHH and RHH. Matz actually strikes out a high percentage of righties than lefties for his career but gives up more power to righties than lefties. He allows a higher BA and OBP vs LHH, but keeps their power greatly in check typically.

This year, facing much more LHH lineups with Yadi behind the plate, it should have set him up (using career norms) for a slightly higher BA and OBP but a MUCH lower slugging percentage against and a MUCH lower isolated slugging allowed (ISO allowed). However, we can see at the bottom of the left side chart that when Yadi catches, he strikes out slightly more batters, but walks a ton more and allows a ridiculously higher ISO despite balls only being hit less than 1 mph harder on average. Now, Yadi calls for a wider assortment of pitches (4 different types instead of 3), but calls for the sinker about 5.5% of the time more often and the slider 6.35% of the time. That leaves just 38% of the time for his curveball (his best pitch, in my estimation) and his changeup.

With Knizner behind the plate, over half of Steven Matz's pitches thrown are changeups and curveballs. He throws 48% sinkers and 0% sliders. Calling for (what I think are) Matz's best pitches, primarily his curve but then his change up next most, more often is likely something that aids Matz's overall numbers with Knizner behind the plate, especially in comparison with Yadi's.

In the chart above with red borders, you can see clearly on the right side column that not only are the batting average (BA), on-base percentage (OBP), slugging percentage (SLG), and weighted on base average (wOBA) higher but so are their expected versions (xBA, xOBP, xSLG, xwOBA) based on batted ball data when Yadier Molina is the one calling pitches behind the plate. Steven Matz has simply been a much worse pitcher with Yadi back there.

That all said, Matz is still well outperforming his expected statistics when Knizner is behind the plate and he's well underperforming his expected statistics when Molina is behind the plate. That all means that while there should still be a gap of Matz's stats with Knizner being better than Matz's stats with Yadi, the difference should not be nearly as large as it is right now...but in actuality, it still is a cavernous gap at the moment.


So let's dig in even more! Which individual pitches have the biggest difference of results between when Matz throws to Knizner vs. when Matz throws to Molina?

In an effort to match up the colors above from the pitch breakdowns from Baseball Savant, notice how sinker has an orange background, curveball has a light blue background, changeup has a green background, and slider has a yellow background in the above chart. Looking at the sinker chart, in a similar amount of plate appearances ending in that pitch, Matz's BA again and OBP against numbers with both Yadi and Knizner are very similar to what would be expected using batted ball data. However, the SLG with Yadi behind the plate has been worse than expected and the SLG with Knizner behind the plate has been better than expected. Not only that, but the expected slugging on sinkers with Yadi behind the plate is much greater. Below is a .gif of the locations of the sinkers and the results on those sinkers. You can see, as you did in Blake Newberry's piece if you read that or clicked through to that when I linked it above, that Matz has thrown many sinkers to that upper left quadrant of the zone. However, with Knizner behind the plate those sinkers have skewed slightly lower in the zone than when Yadi is behind the plate.

Using the chart above showing numbers for each pitch type by catcher, when looking at curveballs we see where Matz's numbers with Knizner has skewed the most favorably as compared to the expected numbers based on batted ball data. The numbers with Yadi behind the plate on curveballs was about as unfavorable compared as they were when sinkers were compared with batted ball data.

When you look at the comparison of curveballs on the .gif above, you can see that Matz throws curves higher in the zone with Molina behind the plate as well. This is leading me to believe that it might simply be a target/glove placement thing between Molina and Knizner that is leading to the pitch location skewing even higher with Molina behind the plate than when he throws to Knizner behind the plate.

When we look at changeups on the chart above, we see that the results should be approximately equal between when Matz throws to Yadi as to when he throws to Knizner. We also should see in that chart that the results simply are not similar at all. They're much worse with Yadi back there. Let's look at locations again.

What I see in that .gif above is that Yadi rarely has Matz find the strike zone on a change up. So batters are able to simply take the change up a lot more often with Yadi behind the plate or crush it if they see it's coming over the plate. Another way to put that is that the change up with Yadi behind the plate has become nearly an uncompetitive pitch as opposed to with Knizner back there. That's doubly bad considering the changeup has had the best results of any pitch with Yadi behind the plate.

We already know that there are no sliders thrown so far this year with Knizner behind the plate, but where does Matz throw it with Yadi back there? The answer? Way too high in the zone. I don't know that he's hit the bottom third of the zone (or lower) with that slider yet this year.

Look at what happened the ONE SINGULAR TIME he may have hit the bottom third of the zone with a slider in 2022. A beautiful backwards K against Kevin Newman of the Pirates.


In fact, when targeting anything ending in a 7, 8, or 9 on this handy chart from Baseball Savant (the lower portions of their "attack zones"), Matz has been pretty darn decent this year. Opposing hitters have batted just .172/.226/.241/.467 off of him in those zones this year. With Knizner behind the plate Matz has thrown to those locations 25.9% of the time but with Yadi behind the plate the number drops to 19.2% of the time. Now, only 31 plate appearances have ended with pitches in those zones, but 11 of those 31 have been strikeouts and only 2 have been walks...and as I mentioned before, the OPS against is under .500 against those locations of pitches.

On pitches that ended up in locations on that chart that end in one through six, Matz has an allowed batting slash line of .358/.409/.556/.965. And yet, that is where he throws 77.3% of his pitches on the year and nearly 81% of his pitches with Yadier Molina behind the plate.


If I have to attempt (as a complete amateur here) to sum up what is going on with Steven Matz through his first six starts with my favorite ball club, it's that he throws too many pitches up in the zone for his pitch arsenal and that he simply doesn't know where his sinker is going often enough to throw it nearly as often as he does.

I don't think that Matz can really do much at this point in his career about the first tweet's fact that his sinker at 95+ mph was typically better than his sinker at 94- mph. He is only going to lose velocity at this point, not gain it. However, moving forward, he has to be able to control his command (if that makes sense) in order for the Cardinals to get enough out of this contract to have signed him to a long-term deal at mediocre pitcher money. If he can't do that, he won't even earn the mediocre pitcher money that he is receiving for the length of contract given to him this past offseason.


Thank you to Nick Childress for the cover art on this article!


bottom of page