I noticed that this blog is read by a good number of Canadians and I suppose that much of baseball Canada is excited: **the Jays just defeated the Rangers and will be playing against either the Red Sox or the Indians in the AL Championship**. I’ll devote this week’s blog post to the Blue Jays in an exploratory study of the outcome of the first pitch.

The batter has to make a decision on the first pitch — should he swing or not? Obviously if the batter swings, he’d like to get a base hit. We will explore the swing rates and the hit rates (on the first pitch) for all 2016 hitters.

### Swing Rates

Using 2016 PitchFX data, I collected the number of PA’s (first pitches) and the number of swings on the first pitch for all batters who had at least a single PA — there were 1103 batters in this group. Now, many of these batters had only a few PAs and one gets a pretty poor estimate at the swing rates for these batters. So I “smoothed” these swing rates using a Bayesian exchangeable model. Below I show a histogram of these first pitch smoothed swing rates.

I think the size of the variation of these swing rates is remarkable. Some batters (think J.J. Hardy, Martin Prado, Joe Mauer, and Curtis Granderson) rarely swing at the first pitch and others (think Yasmany Tomas, Steven Souza, Adam Jones, and Carlos Gomez) love to swing at the first pitch.

### Swing Rate and Hit Rate

The high variation in first pitch swing rates raises an interesting question. **Do players with high first-pitch swing rates tend to perform well on the first pitch? **To answer this, I record the number of balls put in play on the first pitch and the corresponding hit rate (batting average). Below I have constructed a scatterplot of the (smoothed) swing rate and the (smoothed) hit rate for all hitters and added a smooth to see if there is any pattern.

First note that the batting average on balls put in play on the first pitch are higher than typical batting averages — they are centered about 330. Some players have low first-pitch AVG and others have high first-pitch AVG — the range in the smoothed AVGs is between 290 and 380. But I don’t see a general relationship between the swing rate and the AVG, with a comment that the players with a really high swing rate appear to have lower AVGs.

### 2016 Blue Jays

Since the Jays are a playoff team with a powerful offense, I decided on looking at the first pitch swing rates and first pitch AVGs for the Jay regulars.

Several interesting things pop up:

- Most of the Jays (with the exception of Melvin Upton) have middle-of-the-road swing rates between .2 and .3. Melvin likes to swing at the first pitch.
- But there is interesting variation in the first pitch AVGs. Troy Tulowitzki is low (close to .320) while Josh Donaldson (hero of Game 3) and Russell Martin are high (close to .360). I am not sure if these 2016 patterns are real — I’d need to look at more data since AVGs are relatively poor measures of batter talent.
- If I were to look deeper, I’d look at a better measure of batting performance (like linear weights) on the first pitch.