Wrote this and posted it on my site, copied and pasted over here.
The TLDR version:
Most pitches in zone called balls in the league
Largest difference between perceived velo and actual velo
xBA + xwOBA both say he's been the unluckiest pitcher in the league, even though by that hes still been average at best
Has the third fastest fastball in the league by perceived velo (as a SP)
A little over a month ago, I had written about Tyler Glasnow being the recipient of some atrocious umpiring. My assumption was that he was simply the victim of a small sample size, and given a larger sample size, his misfortune would even out. That hasn't been the case. In fact, no other pitcher has gotten more ball calls on pitches thrown in the zone than Tyler Glasnow.
Despite the ongoing bad calls, he has managed to consistently lower his ball rate. As you can see below, three out of his first four starts were far from ideal. However, since then, he's been much closer to league average. His last five starts have been right around league average, and in his previous two starts he's actually thrown less balls than the league average.
Obviously, balls mean walks, walks mean baserunners, and baserunners lead to runs. Runs are bad, so less balls are generally better. The more recent version of Tyler Glasnow has thrown less balls than the earlier version, but the results haven't been great. Over his last five starts he has a 5.96 ERA and a 5.71 FIP, while still walking 11.2% of batters he has faced. The numbers have gone from terrible to just really bad.
Despite the league average ball rate, he is still walking 11.2% of batters over his last 5 starts, which is above the league average walk rate of 8.7%. His 11.2 BB% is certainly an improvement over his 15.5 BB% from his first four starts. There is certainly room for improvement, but I don't think he needs to improve much more to get significantly better results.
Tyler Glasnow survived in the minors because of one thing: stuff. At just 22 years old, Glasnow managed to strikeout 30.4% of the hitters he faced in AAA last year. You simply can't do that without incredible stuff. At this point we all know that his strikeout rate comes with an equally impressive (or depending on how you look at it, unimpressive) walk rate.
But, what often gets ignored from his minor league career is his very low BABIP at each level that he's played at. His low BABIP could mean a few things. First, it could mean he simply got lucky. Second, it could mean that his team had good defense. The go to explanation when referring to BABIP is the first reason, luck. However, I think that his low BABIP in the minors could, at least somewhat, be attributed to hitters being unable to square him up.
So far this year, Glasnow has given up good contact on only 9.16% of the balls put in play against him. That has him ranked 26th best in the league, ahead of guys like Jacob deGrom, Dallas Keuchel, and Clayton Kershaw. He's also ranked above teammates Chad Kuhl, Gerrit Cole, and Ivan Nova.
Considering that he hasn't given up much good contact, it's weird that opposing hitters have managed a .302 batting average against him. But, his xBA suggests he has gotten extremely unlucky. He has the biggest gap between his xBA and actual BA in the league (Chad Kuhl is 4th). According to Baseball Savant, Tyler Glasnow has an expected batting average of .250. If you wish to read about xBA, you can do so here. If you don't wish to read about it, I'll explain it briefly anyway. It takes hit probability, which is determined by exit velocity and launch angle, and uses that to come up with an expected batting average. Why would a player have a difference between their xBA and actual BA? Again, it comes down to team defense and luck. In actual BA, defense and luck are a factor. But a pitcher has no control over their luck, or their team defense. So, it's best to remove them altogether which is why xBA is preferable.
Batting average is a fine stat, and is perfect to use for what I am trying to show, Glasnow has been a bit unlucky. But wOBA is a far better overall statistic. xwOBA is much like xBA, the only difference is it calculates the expected wOBA instead of expected BA. Once again, Glasnow has the biggest gap between his xwOBA and wOBA (Chad Kuhl is right behind him). If you assume his xwOBA should be his wOBA, his wOBA would still be below average in the league. However, being slightly below average is still better than being one of the worst in the league like he is now.
John Jaso has been awful in right field for the Pirates. Nobody has cost their team more runs in right field than him. Since Glasnow is a right handed pitcher, teams like loading up their lineup with lefties (this could explain some of Kuhl's problems as well). Lefties, just like righties, tend to pull the ball. Lots of lefties pulling the ball results in lots of balls hit to John Jaso. Getting Gregory Polanco (and eventually Marte) back in the outfield should be a huge boost to both pitchers production going forward.
The featured image used for this post is used without context. Below, it's used with context.
As Daren Willman found, Glasnow is off the charts when it comes to the extension he gets and the perceived velocity it helps generate. The reason for his upside, and one of the reasons for his current downside, is his height. His height makes his delivery hard to repeat, which is why he has no control. But his height also brings a larger wingspan. As explained here, his long wingspan allows him to hold the ball longer than normal.
The longer a pitcher can hold onto a ball, the higher the perceived velocity. Glasnow already throws hard. He currently possesses the 34th fastest fastball out of all starters. His 94 mph fastball is certainly fast. However, the image above shows why his fastball is better than just a 94 mph fastball. His height allows him to get such good extension, that his perceived velocity is 2.5 mph faster than his actual velocity! All of a sudden, his 34th fastest fastball becomes the 3rd fastest fastball behind Stephen Strasburg and Luis Severino, but ahead of guys like Jameson Taillon, Chris Archer, and Chad Kuhl.
This season has been a season of extremes for Glasnow. He is a huge outlier in many aspects. His height has cursed him with poor control, but has blessed him with great perceived velocity. He may never have great command, but I do think he will need average control to succeed. Command is the ability to throw pitches exactly where you want whereas control is simply the ability to throw strikes. Glasnow can get away with missing his spots, since his stuff is so good. All he will need to do is be able to throw strikes, and make hitters beat him. They weren't able to hit him at any level in the minors, and they haven't been making great contact so far this year. He is still just 23 years old, and clearly has the stuff to dominate at this level. He may never put it all together and become an elite starter. But he's not far from putting a little bit together, and becoming a volatile back of the rotation arm.