The Most Important Skill For Pitchers Is Throwing Two Strikes
There’s a lot of data I look at to evaluate pitchers. Contact rates (the quality of their pitches) and how often they get swings outside of the strike zone are two of the most important factors I use to determine if a pitcher is pitching well or not. How often they throw strikes is another. But better yet, I think the most important skill for any pitcher is throwing two strikes early in the count, the ability to get to two strike counts.
Most aspects of a plate appearance are innocuous. A pitcher can throw a ball or a strike and a hitter can swing or not swing and most of the time nothing happens. The hitter either takes the pitch, swings and misses, or fouls the ball off. Only when the hitter makes contact and puts the ball in play does anything significant happen.
This means mistakes by a hitter are less damaging in non two strike counts. A hitter can take a huge rip at a pitch way outside the strike zone and look like an idiot, but all that happens is one more strike in the count. He’s still alive. Before two strikes are thrown, the hitter has the advantage. He can choose to swing at whatever pitch he wants without consequence.
But when a pitcher has thrown two strikes, the game drastically changes. Suddenly, any strike thrown without contact becomes an out. The pitcher now has a huge advantage. Any called strike or missed swing now becomes immensely more valuable. Now with two strikes, the hitter can record in out without even the chance of hit from putting the ball in play.
The data backs up the pitcher advantage with two strikes tremendously. Let us look at the league average count splits from 2016. For any non two strike count, the league average OPS is over .800, and in most cases over .900. Excluding full counts, with two strikes OPS drastically decreases to below .500. The ability to record an out without putting the ball in play is unique to two strike counts, and is a gigantic negative for the hitter.
Because two strikes is such an advantage for the pitcher, throwing two strikes as fast as possible would seem to be the ideal strategy against any hitter. But there is one inherent problem with trying to get to two strikes quickly, you either have to have great control or need to aim at the middle of the plate. Unsurprisingly, the best location for a hitter to swing at a pitch is right down the middle, and quality of contact gets progressively worse as we get further from the middle of the plate. We can see this visually by looking at Fangraphs league average heatmap for 2016, but other years are no different. A ball contacted down the middle of the plate is much more likely to do damage than one at the edges of the strike zone. And if the hitter knows a strike is coming early in the count, they can swing early and possibly get good contact, better than they would have if a pitcher took a less aggressive strategy. The two strike strategy then would only be good strategy if the advantage of putting two strikes in the count is greater than the disadvantage of location and predictability leading to better contact early in the count.
One way we can see how much better contact hitters get against an aggressive strike throwing strategy is by looking at the relationship between exit velocity and how often a pitcher throws in the strike zone. Throwing pitches in the strike zone rather than out of the strike zone should result in harder contact as suggested from the league average heat map chart.
However, looking at 2016, up to August 12th, the correlation between Zone% (how often a pitcher throws the ball in the ztrike zone) and exit velocity is approximately -0.1, a slightly inverse relationship! There are some confounding factors here, pitchers with better control will probably have a higher Zone%, and better pitchers tend to have lower average exit velocities (exit velocity allowed and an ~-0.3 correlation with ERA minus). Nonetheless, the inverse relationship between Zone% and exit velocity suggests that contact is so much worse with two strikes that throwing the ball down the middle to get there is a smart trade-off.
The list of pitchers best at getting to two strikes further supports my argument. I queried the Pitch F/X database at baseballsavant.com for percent of pitches thrown at 2 Strike or 0-1 counts in 2016 (I included 0-1 because at 0-0, getting to 0-1 is the best a pitcher can do to get to two strikes). This is basically how “fast” pitchers get to two strike counts. You can look at the results here. When Max Scherzer and Clayton Kershaw are two of the top 10, both easily the best pitchers in baseball, it makes me think I’m onto something. There are some weird pitchers like Juan Nicasio and Mike Foltynewicz on the list, but the top is mostly great pitchers like Strasburg, Bumgarner, and Quintana. Francisco Liriano, who was in dead last at the time I started writing this article, is arguably having the worst year of his career and is one of the worst pitchers in baseball. Maybe this is why.
I can imagine there are opposing hitters where the get to two strikes strategy would not be good, mostly the best hitters in baseball. A hitter with great contact rates and who hit for a lot of power may do too much damage in the middle of the plate or sweet spot for that player to make getting to two strikes worth it. If they have good contact rates, they aren’t likely to swing and miss anyways, so getting there isn’t as important. This is probably why pitchers chose to walk Barry Bonds an overwhelming amount in his prime. But pitching strategy should obviously depend on the opposing hitters approach and attributes. Most hitters aren’t Barry Bonds, and I could imagine with 99% of opposing hitters, getting to two strikes is a pitcher’s most important goal.
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