Fastball Quality Matters …

Last week, I examined if throwing too many four-seam fastballs led to a pitcher being predictable and getting hit around. What I noticed was that I needed to expand out past just four-seamers and include sinkers. Again, I failed to find a connection between fastball quality-and-quantity and weakly hit batted balls. Instead, I was able to determine some benchmarks to find good fastballs.

Through some observations, I believed that throwing too many fastballs, especially if they were of poor quality (e.g. slow, average spin), would get hit harder. I dug through the numbers just hoping for my thoughts to be verified but I found jack squat. Nothing.

Most likely, I was digging too deep. In trying to find what I hoped for, I created a complex fastball valuation method that includes:

• Pitch characteristics grades: Stuff+ and Pitching Bot. I found that a pitch’s combined (Overall and Pitching+) value to be more predictive (e.g. K%) than the pitch’s “stuff” value.
• Pitch results (swing-and-missed, flyball): pERA
• At-bat events off fastballs (strikeout, home run): The pVal/100 values on the player pages.
• Average of both the sinker and four-seam results.
• The total percentage of the fastball compared to total pitches.

I combined the first three values using z-scores, weighed that value by pitch usage, and finally considered fastball usage. It was way too complex, but like I mention, I was dropping all the stops.

Just like in the last article, I didn’t find a direct with fastball velocity. An interesting note was that the best and the worst pitchers had the highest velocity. The good pitchers and higher velocity makes sense. For the bad pitchers, I wonder if they just thought the velocity would carry them and they overuse their fastball.

Using that fancy pants value, here are the leaders and laggards from 2021 and 2022 (only two seasons with STUFFF values).

No one seems out of place in those rankings.

After creating the fastball quality metric, I have zero interest in using it, especially during the season. It’s just way too time intensive to create and some of the values aren’t easily accessible. Even then, each of the two fastball values need to be combined and weighted. Instead, I came up with some simple benchmarks on what is a Plus fastball.

• Pitch+ (Stuff+): Min 95 about best at 100 or higher
• Overall (botStuff): Min 50 and best at 55 or higher
• pVal/100: Over -0.5. This value has a ton more variability than the other so it has a larger acceptable range.

Make sure to take usage into account. For example, Corbin Burnes has horrible four-seam grades but he has only thrown the pitch 0.5% of the time.

Here are the starters from this season whose fastballs meet all the available criteria (link to full table). I ignored pitch usage so some elite arms might have gotten filtered out.

Again, no real surprises.

While I run a query against the StatCast database to get my pERA values, those values aren’t accessible to the public. The pERA values are created from the pitch’s swinging-strike and groundball rates. They can be found on the player pages. Also, the leaderboards for each value are available on Savant (swinging-strike rate and groundball rate).

A 7.0% SwStr% is fine with 10% ideal. As for the groundball rate, values under 30% GB% (generates popups) and over 55% (generates groundballs) are the benchmarks.

Again, I found nothing on fastball quality limiting hard contact, but through the process I found a greater appreciation of what makes up a good fastball and will target those pitchers who throw them.