Early Plate Discipline Improvers

April 30, 2021

Jon Anderson identifies hitters that are showing better plate discipline in 2021 with lower strikeout rates (K%) and higher walk rates (BB%), as well as diving into Statcast metrics like Swing% and Chase% to find fantasy baseball underachievers.

Early season data is never very reliable. When you are still in the first month of the season, one game can have a big impact on a player's stat line in most categories. That makes it somewhat foolish to look at the data until you at least get a month or so of games out of the way.

One exception to this is plate discipline numbers. These numbers tend to stabilize much quicker than other performance markers for a couple of reasons:

1. The denominator grows much faster in these categories than others. By this, I mean that most of these "rates" statistics are being divided into total pitches seen rather than into at-bats or plate appearances. That gives us a significant amount of data much quicker.
2. These are often better indicators of true skills. Contact rate, for example, is not influenced by anybody but the pitcher and the hitter. With other statistics, much more luck enters the picture when you start including events that happen after contact is made.

In this post, we will highlight a handful of plate discipline statistics and see which hitters have improved in these areas in 2021. For the sake of sample size, I am comparing 2021 data against 2019 and 2020 totals.

Contact Rate

Contact Rate, the way I use it, is defined by the percent of the time a hitter makes any kind of contact (foul balls included) on all of their swings. Here is the full list of players that have increased their contact rate by 3% or more in 2021 (data current as of April 28th).

The only chink in the armor of Ronald Acuna Jr. in his young career has been the swing-and-miss. Prior to 2021, he had routinely posted strikeout rates in the mid-20s. This year, he's lowered that to 15.2% and that is on the back of true improvement under the hood, as evidenced by his huge gains in contact rate. He has also posted big walk rates the last two seasons. That probably has more to do with pitchers just not wanting to face him after he's proven himself to be one of the best hitters in the league, but he is clearly improving his plate discipline. It will be incredibly interesting to see how big of a year Acuna ends up having.

Talking about Acuna does not do fantasy managers much good, so let's look at some other names near the top of the list. Raimel Tapia has raised his already high contact rate and that's despite facing the Dodgers' strikeout-happy pitching staff twice. He should continue to be an elite source of batting average. We see a few fantasy hitters that were elite despite their high strikeouts and are now improving in that regard here as well. Aaron Judge, Nelson Cruz, Austin Riley, and Matt Olson have flashed good signs early on and might not be the batting average craters they have been in their careers moving forward.

Some potential buy-low options here: Travis Shaw, Rougned Odor, Mark Canha, Yasmani Grandal, and Brandon Lowe.

Chase Rate

Chase rate is defined as the percent of pitches out of the zone that a hitter swings at. This is a large part of where strikeouts come from. It is obviously harder to put a bat on a ball out of the zone, and the best hitters are ones who can identify those pitches and not swing. Here are all the hitters that have improved their chase rate by seven percent or more.

You can see that there's some juice behind Evan Longoria's hot start to the year, as he seems to be seeing the ball better this year. This is also very good news for players like Eduardo Escobar, Max Kepler, Victor Robles, Austin Riley (again), and Vladimir Guerrero Jr. The first four listed there were fringe fantasy players that have (or could soon) become very useful fantasy bats. And seeing any kind of improvement from Vladito is just frightening given what that guy can do when he gets his pitch. He's looked fantastic this year and seems to be making the strides most people figured he would.

Swing% and BB%

I'm tying these two in together because of the strong correlation between them. I took all qualified players between 2019 and 2020 and found their swing rates (the percent of pitches they swing at) and compared them with their walk rates. Here's what that plot looks like:

You can see the downward trend visualized nicely there; this is a negative correlation. As your swing rate goes up, your walk rate will go down. This is perfectly expected given that you need to see at least four pitches to draw a walk, so every swing you take decreases your odds of earning a free pass.

Let's take a quick look at the lowest swing rates for 2021 as things currently stand.

Indeed, we see a ton of high walk rates (the league average walk rate is about 8% for reference). Grandal and Muncy are just making a joke out of things. They have no interest in swinging the bat until they are forced to, and that has manifested in massive walk rates. This has not actually helped fantasy teams in non-OBP leagues so far, as neither guy has piled up many runs scored from all the times they've been on base. Their lack of speed and placement in the batting order are the primary reasons for this. It would not be crazy to try to ship these two guys away in a rotisserie league that doesn't use OBP.

You see a lot of names here that aren't very interesting for fantasy purposes. However, they could be nice additions in an OBP league with deep rosters. A high walk rate for a base-stealing specialist like Dylan Moore is a very good sign. He is going to strike out a ton, but if he can get on base 30% of the time he should pile up some steals even while hurting you in nearly every other category.

David Fletcher defies logic a bit here with his low swing rate and walk rate. I would imagine part of the reason for this is just because pitchers are throwing him tons of strikes with Ohtani and Trout batting behind him and his lack of power. Pitchers really don't want to walk him because the worst he will likely do to them is a single if he gets a pitch to hit. He's good for some batting average and runs but I wouldn't be expecting any decent walk rate moving forward.

K%-BB%

This is probably my favorite statistic to look at on both sides of the ball. The ideal hitter has a low strikeout rate with at least an average walk rate. Here's a scatter plot visualizing all qualified hitters with their two rates. You can hover over each dot to see who it represents. The "best" hitters in this visual will be in the lower right quadrant, which denotes a high BB% low strikeout K%.

And now here's some hard data in table format showing the top 50 hitters in K-BB%.

Very encouraging to see Guerrero near the top again. The biggest shock on this table is Yuli Gurriel, who is absolutely demolishing his career walk rate this year. Since 2016, he has a tiny 5.2% walk rate, and you can see how much that has increased this year. He checks every box in this analysis, swinging less (-6.6%), chasing less (-7%), and walking more (+10.6%) while his strikeout and contact rates have stayed steady.

Five names have decreased their chase rate by 5% or more while increasing their contact by the same amount. Those names: Raimel Tapia, Austin Riley, Kyle Farmer, Ronald Acuna Jr., and Mark Canha. I would be excited to roster these names (besides Farmer who does not have a starting job) moving forward.

The metrics I talked about above are often the first signs of serious box score improvement. You can use the above information to find some potential waiver pick-ups or buy-lows in trades. Good luck!

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