# Attacking the First-Pitch Strike

I have a few bugbears when I watch a baseball game. I feel most of these are derived from the fact that I have never been taught how to play the game or faced something being thrown at me faster than 50 mph. A lot of these are behavioral or unwritten rules, but some leak into how the game is played.

The thing that I don’t understand the most is the first pitch called strike. Below are videos of Nolan ArenadoMike Trout, and George Springer all taking first pitch called strikes.

These videos are prime examples of something I struggle to get my head around. All three were in zone 5 of the diagram below, an 8-inch by 6.6-inch square in the middle of the zone, with speeds of 91 mph or below. In the last one, Springer is taking a first pitch strike right down the middle of the plate, a 91-mph fastball from Matthew Boyd. To me, that was very hittable pitch. And if you have decided to leave that pitch, as far as I am concerned, you have made a mistake.

People will say that it was the first pitch that Springer saw that game, and that it was even the first pitch of the game, and that batters need to get their eyes in. Some might say that a hitter should build up the pitch count of the pitcher and early swinging is bad for that. But let’s look at this analytically to see what they should be doing.

I examined data from the 2018 season to see what was going on. Thanks to the Statcast data made available by MLB, we have access to details of 800,000 events across 200,000 at-bats.

For the rest of this article I will be concentrating on where the pitch crossed the plate using the zones shown previously, as the diagram above gives you the size details of the zones. This zone split was created by Tom Tango and the MLB Statcast team. It does a better job of describing plate discipline and outcomes for hitters rather than simply looking at if a pitch was in or out of the zone.

Waste Zone = Ozone from the diagram

The table above shows the how often a pitch was thrown into each zone in 2018, how likely a hitter is to swing on that pitch, and how likely they were to miss on that swing. As you can see, there is distinct difference between how the average major league hitter behaves when pitches are thrown in these different zones. This leads to different outcomes when they make contact.

The following table uses the expected batting average (xBA) and expected weighted on base average (xwOBA) stats generated by Statcast, which are based on exit velocity, launch angle, and on certain types of batted balls, sprint speed.

Unsurprisingly, we expect hits on balls in the heart of the zone to produce, on average, better results than pitches located in any other zone. As with the changes in hitter swing behavior, the outcome differences are pronounced. With that in mind, if you get a pitch down the heart of the zone, you really want to be hitting that into play.

Let’s look at our 0-0 counts and what did batters saw and did on the first pitch in 2018.

For the first pitch, pitchers will put the ball over and around the plate more often than the average pitch, and if we look the swing rate, we may see why. There is a massive reduction in swing rate at pitches for all areas. For pitches that are down the heart of the plate, hitters only swung 46.5% of the time, which when you compare that to the 70.6% average, it seems like a massive missed opportunity here.

But the average for the season isn’t actually that telling, so let’s see how the 0-0 count compares to other counts for pitches in the heart of the zone. We are concentrating here on just heart of the zone pitches as I believe that is where the greatest gain could come from.

As you probably would have anticipated, the likelihood that a pitch is thrown in the heart of the zone is dependent on the count, with more thrown in hitters’ counts and less in pitchers’ counts. Also, the behavior of the hitter is dependent on the count, with higher swing rates on pitcher counts and lower swing rates on hitters counts.

What does stand out to me is how vastly different — around 20 points lower — the swing rate on 0-0 is to all of the other neutral counts (1-0, 1-1, 2-1). When a hitter does make contact, the xwOBA for balls in play is fairly similar.

Side note: Even though the swing rate is really low for 3-0, hitters shouldn’t necessarily swing more often as the wOBA for at-bats through 3-0 is 0.551 and the xwOBA on hits in the 3-0 count is 0.535. It is all context-dependent though, as there is a large HR rate for this swings.

So what is happening here? Does seeing just one pitch mean that a player has their eye in to such extent that they are willing to swing 40% more at a 1-0 pitch than a 0-0 pitch? Or is this more of a set approach?

One thing which might make a difference is the number of times the batter has seen that pitcher in the game, so let’s look again but split this data based on the number of times faced in the game. Let’s start with the pitchers. (This for heart of the plate pitches only.)

In nearly all counts, the pitcher reduces the percent of pitches that end up in the heart of the zone. (3-0 shows increases but the volumes are significantly smaller than others). The decrease isn’t that significant though, and it isn’t on the scale as the difference seen for hitter and pitcher count types.

So, the pitchers make a small adjustment, but how about the hitters.

We see an increase in swing rate in all scenarios from the first time seeing a pitcher to the second and third times, with the most significant increase seen in 0-0 (we are ignoring 3-0 again due to the low volume).

There is something here, and hitters are more likely to swing when they have seen the pitcher already in a game, but the highest swing rate for 0-0 (52.4% the third time through) is still less than the swing rate for any of the other neutral counts the first time up.

The performance of the at-bat is better than the average at-bat (.315 wOBA) for all of these scenarios, which suggests that a hitter should swing more often.

It is even worse if we look at just the first pitch of the game, as the ball is thrown down the heart of the plate over 30% of the time but the batter swings on those pitches just one third of the time. In 2018, the 245 at-bats that put the ball into play on pitch one of the game had a wOBA of .503, which is 60% better than average.

Based off of all of this, I believe that there is a mindset/approach difference to the 0-0 pitch compared to all other at-bats. Hitters seemingly see enough with just one pitch to significantly adjust for the next pitch, but they don’t see enough over two full at-bats to adjust on the first pitch of the third at-bat to the same degree.

So far, we have concentrated of pitches down the heart of the zone and suggested that swinging more in that scenario would be better for the hitter. But if we expand back to all pitches, you will see that when the hitters swing at pitches in the heart of the zone more often, they swing at pitches in the chase zone and shadow zone more as well.

What if the hitter behaved more like they did in other counts?

Looking at the pitch location data, we can see that the approach of a pitcher is pretty similar, location-wise, at 0-0, 1-0, and 2-1. But the swing rate change from 0-0 to 1-0 and 2-1 is significant across the board. Let’s project a world in which the hitters like 1-0 or 2-1 at 0-0 and see what difference it would have.

In 2018, the league-wide wOBA was .315 and the wOBA for the 1-0 and 0-1 counts was .357 and .269, respectively. With these and the number of occurrences of each of these counts, I calculated the wOBA for at-bats that end on the first pitch as .377, which is 20% better than average. Using these values and taking the assumption that all at-bats would behave exactly the same after the first, I got the following wOBAs.

The overall wOBA if hitters swung like they do for other counts is an increase for both 1-0 and 2-1. The increase isn’t that high, as the strike-to-ball ratio is higher for these counts. This translates to an extra run every eighth game for the 1-0 count and an extra run every third game for 2-1.

The data shows that hitters swing more and get better results the more times they face a pitcher, so is there something that can be done here so that they are more ready for the first pitch? One company that I know of certainly thinks so.

When I was at the SABR Analytics Conference that occurred during spring training this season, there was a stand from a sponsor of the event called Trinity VR. At the event, you could put on a set of VR goggles and take an at-bat with a motion sensor and face some pitches.

I am not talking about the pitches that a few of you may have seen at the London Yards event during the MLB London Series. I am talking about real pitches with accurate ball-flight path, spin, and physical pitching dynamics. I faced Trevor Bauer 10 times and got nowhere near any of them, as my only saving grace was not swinging on one that end up in the virtual dirt.

They say that studies have demonstrated the efficacy and transfer of batter performance from virtual environments to the real world. If this is the case, then teams and players should be looking into this, as this could help with swinging more on those first pitches down the middle.

This is a known market inefficiency, as last year Tom Tango did a piece of work which calculated the run value of taking or swinging on certain pitches based on the same four zones we have discussed. His analysis showed that taking pitches in the heart of the zone at 0-0 counts cost a batting team 3.8 runs for every 100 occurrences, while swinging earns the team 1.5 runs per 100 occurrences.

Ben Lindbergh recently showed that hitters are increasing their swings on first pitches, and this data shows that there is still potentially more that can be done. I am not suggesting that hitters should just swing more often on any first pitch, but that they should be better prepared for the pitch down the middle and swing on that when they get it. Simply put, any player or team that can improve on this will be able to make gains on the others.

This piece originally ran on July 30 at Bat Flips and Nerds.

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