Tom Glavine’s Allegedly Generous Strike Zone

People don’t really argue about Tom Glavine anymore. It’s been some years since he pitched, and we have younger, Troutier, Cabreraier things to argue about. But when people did argue about Tom Glavine — and they used to do it a lot — his critics routinely pointed to the same thing. And when Glavine was voted into the Hall of Fame just the other day on the first ballot, the old familiar argument popped up again in certain places. Glavine, many people believe, was a product of a strike zone that extended several inches off the outside of the plate.

An alleged strike zone, it should be said, that Glavine kind of allegedly earned. The theory is that Glavine established that area and was given the benefit of the doubt by the umpires because he could so consistently put the ball there. So, with his command, Glavine was said to get strikes on balls. That would be a credit to his ability, but that also puts hitters at a disadvantage, and a lot of people want to know how Glavine would’ve held up under a more uniform zone. There’s a belief that, had Glavine been more squeezed, he would’ve been punished more often. The only problem is that Glavine doesn’t seem to have been a product of his strike zone at all.

In one sense, it’s an impossible thing to investigate since most of Glavine’s career came before the dawn of the PITCHf/x era. But then, it didn’t come before the pitch-by-pitch-data era, which can work perfectly well enough for our purposes. Baseball-Reference has pitch data going back to 1988. That’s the same year Glavine became a full-time big-leaguer.

Of course, we don’t need to look at Glavine’s entire career. The part we’re really concerned with is the part that made Glavine who he became, the part that made Glavine a Hall of Famer. We needn’t focus on Glavine’s mediocre beginnings, and we needn’t focus on his wind-down with the Mets. Let’s just go ahead and isolate Tom Glavine between 1991-2002. Over those years, all with the Braves, Glavine accumulated the vast majority of his career WAR. Those are the years for which Glavine’s most known.

Now, the theory is that Glavine got to pitch to a wider zone than other pitchers. It’s basically the pitch-framing argument, except in this case people prefer to give more credit to the pitcher than to the catcher. In any event, this is something we should expect to see reflected in Glavine’s various rates of called strikes. If Glavine was getting more pitches out of the zone called strikes, we’d expect to see higher called-strike rates, since hitters would be more likely to take those pitches. That’s going to be our primary indicator.

In 2002, there were 126 qualified pitchers around baseball. Glavine ranked 23rd in called strikes per strike, and he ranked 47th in called-strike rate overall. In 1991, there were 116 qualified pitchers around baseball. Glavine ranked 85th in called strikes per strike, and he ranked 77th in called-strike rate overall. Below, a chart with all the data, expressed as percentiles among qualified big-leaguers. The higher the bar, the closer Glavine was to the league lead.

In called strikes per strike, Glavine maxed out at the 89th percentile in 2001. Overall, over the 12 years, he averaged the 46th percentile. In called-strike rate overall, Glavine maxed out at the 80th percentile in 2000. Overall, he averaged the 39th percentile. He averaged the 66th percentile in called strikeouts/total strikeouts, and he led baseball in called-strikeout ratio in 2001, but Glavine wasn’t a low-contact pitcher. The denominator there includes swinging strikeouts, and Glavine didn’t rack up a bunch of swinging third strikes, so his called-strikeout ratio looks higher. His overall rate of called strikeouts per plate appearance hovered in the vicinity of league-average.

You can see those bars sort of increasing over time. In called strikes per strike, Glavine averaged the 25th percentile between 1991-1995, and the 61st percentile between 1996-2002. As he got older, he started to get more strikes looking, but for one thing, he was good before that, and for another, his numbers were never crazy high. The way people talk about it, Glavine got one of the most generous strike zones ever. He actually had a far lower called-strike rate than Aaron Sele. He had a far lower called-strike rate than Livan Hernandez. Other high-called-strike pitchers included John Burkett, Matt Morris, Kirk Rueter, Frank Tanana, and Charles Nagy. Eventually Glavine got perhaps a more generous zone than average, but that isn’t the point that people argue. People argue his zone was particularly unfair, and that just doesn’t show up. Not during Glavine’s career prime.

What Glavine did do was suppress hits, even beyond getting help from Andruw Jones. He changed his approach with runners on base, issuing more walks while reducing quality contact. He was also terrific at suppressing home runs. Over those dozen years, 95 pitchers threw at least 1,000 innings, and Glavine ranked third in ascending order of dingers per inning, behind Greg Maddux and Kevin Brown. In these ways, Glavine managed to out-pitch what might be suggested by his raw rates of strikeouts and walks.

Even toward the end of his career, Glavine worked almost exclusively low and away against righties, and almost exclusively low and away against lefties. He went to other areas just often enough to change it up and keep the hitters guessing. His command was good enough to allow him to hammer those zones, and it’s no coincidence those are the zones where it’s most difficult for hitters to do real damage. When you pitch around the edges, you’re more likely to miss the edges, and you’re more likely to throw balls. Glavine never actually posted a particularly good strike rate. This can be offset by inducing weaker contact, which Glavine’s career demonstrates. And because Glavine threw a greater percentage of pitches away, from time to time he’d end up with a called strike that missed the plate completely. He wouldn’t necessarily get an extraordinary amount of them, but it doesn’t take many to stick in the memory. Glavine didn’t get way more called strikes than the rest of the population — I just suspect he got his called strikes in the same consistent areas. That’s what happens when you pitch to the same two spots.

This doesn’t conclusively prove anything. I imagine Glavine did have a more forgiving strike zone than the average pitcher, and he got more called strikes as he got older, potentially helping him to mitigate a career decline. It’s possible umpires were more willing to give him the benefit of the doubt. Certainly, he would’ve wound up with his share of called strikes over the borders of the opposite batter’s box. But, there’s a line of thought that Tom Glavine was a product of a skewed strike zone, biased in his favor. There’s a line of thought that Tom Glavine would’ve performed a lot worse if he had to pitch to more normal areas. The data suggests this isn’t actually true. What Tom Glavine was was a hell of a starting pitcher. For hitters, the opponent to worry about wasn’t the umpire. The opponent to worry about was Tom Glavine.