The Called First Pitch Strike – Why?

I have a few bugbears when I watch a game of Major League Baseball, 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 behavioural or unwritten rules but some of these leak into how the game is played.

And the thing that I don’t understand most is the first pitch called strike.  Below are videos of Nolan Arenado, Mike 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, a 8” x 6.6” square in the middle of the zone, with speeds of 91 mph or below. In the last one George Springer is taking a first pitch strike right down the middle of the plate. It was a 91 mph fastball from Matthew Boyd. To me, that was really hittable pitch.  And if you have decided to leave that pitch you, as far as I am concerned, have made a mistake.

Now people will say that it was the first pitch that Springer saw that game, 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 if what they should be doing.

Let’s look at the data from the 2018 season to see what was going on. Thanks to the Statcast data made available by MLB we access to details of 800k events across 200k at bats.

For the rest of this article I will be concentrating on where the pitch crossed the plate using the zones shown previously, 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 at describing plate discipline and outcomes of hitters than simply looking at if a pitch was in or out of the zone. 

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 stats (xwOBA) generated by Statcast, these 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 that pitches located in any other zone. As with the changes in hitter swing behaviour, the outcome differences are pronounced. So, if you get a pitch down the heart of the zone you really want to be hitting that into play.

So let’s look at our 0-0 counts, what did batters see and do for 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 which are down the heart of the plate MLB hitters only swung 46.5% of the time, which when you compare that 70.6% normal it seems like a massive missed opportunity here.

But average of the season isn’t actually that telling, lets 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 dependant on the count, with more in hitter counts and less in pitchers counts. Also, the behaviour of the hitter is dependant 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 they probably shouldn’t 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 dependant 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 lets 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 small than others). The decrease isn’t that significant though, it isn’t on the scale as the difference seen for hitter and pitcher count types. 

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

We see an increase swing rate in all scenarios from 1^st time against a pitcher to 2^nd and 3^rd time. With the most significant increase scene in 0-0 (we are ignoring 3-0 against due to the low volume).

So 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% 3^rd time through) is still less than the swing rate for any of the other neutral count first time up.

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

It is even worse if we look at just the first pitch of the game, 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 an pitch one of the game had a wOBA of .503, which is 60% better than average.

Based off all this I believe that there is a mindset/approach difference to the 0-0 pitch then all other at bats.  But hitters seemingly see enough with just one pitch to significantly adjust for the next pitch but don’t see enough over 2 full at bats to adjust on the first pitch of the 3^rd 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 the 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 another count.

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 & 2-1. But the swing rate change from 0-0 to 1-0 & 2-1 is significant across the board. Let’s project a world where the hitters like 1-0 or 2-1 at 0-0 and see the difference it would have.

In 2018, the league wide wOBA was .315 and the wOBA for the 1-0 & 0-1 counts was .357 & .269 respectively. With these and the number of occurrences of each of these counts I calculated the wOBA for at bats then 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 the 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. The extra runs is what we would expect across an entire season of MLB, this translates to an extra run every 8^th game for the 1-0 count and an extra run every 3^rd game for 2-1.

The data shows that hitters swing more and get better results the more time they face a pitcher, so is there something that can be done here so that they are more ready at pitch number 1. One company that I know of certainly does.

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

I am not talking the pitches that a few of you may have seen 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, 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 swinging more on those first pitches down the middle, as this should help the team.

This is known market inefficiency, 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 4 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 and swinging gains the team 1.5 runs per 100 occurrences.

Ben Lindbergh recently showed that hitters are increasing their swings on first pitches, 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.

Anyone or team that can improve on this will be able to make gains on the other teams.