Pitcher Injury Finder & Fastball Grades

Fastball velocity changes may be getting beat to death but they are one of the few stats in which stabilize early in the offseason. I’ve created a couple tools which I use during the season to help find which pitchers to evaluate further using velocity. I have one which grades fastballs and a new pitcher injury finder.

Fastball Grades

This tool simply gives an ERA and 20-80 grade to a fastball based on its projected results from its velocity and spin. The velocity component is simple to understand. It’s hard to hit fast flying small objects. It’s even harder to hit faster flying small objects. Understanding the spin component is a little tougher.

The spin dictates how much a pitch will drop or rise. Hitters are used to a certain speed fastball having a set flight path to the plate. If the spin is more or less than normal, the ball will drop more or less and the hitter will make contact under or over their desired contact point. Too high on the ball means a ground ball. Too low, a popup.

It is ideal for a pitcher to have his fastball spin rate as far as possible from the norm. For a reference, here are the average fastball spin values for various pitch velocities

As it can be seen, the harder a pitcher throws, normally the ball spins more.

So using velocity and spin, I can estimate the pitch’s swinging strike rate and groundball rate from past results. Then, I inputted the values into my pERA equation and came up with an ERA for just that pitch. Finally, I took the pERA values, found the average value and gave it a grade of 50 (average major league fastball). For each standard deviation above average, the grade goes up by 10 with 80 being the best and 20 the worst.

With the explanation out of the way, here are the top and bottom ten fastballs in the league so far (full list).

Now, other fastball factors can be in-play besides velocity and spin like deception, control, command, and sequencing. It’s a quick-and-dirty test for a snapshot to help find pitchers to investigate further.

At some point in the future, I’d love to be able to run this process with any pitch but for now, it’s just fastballs.

Pitcher Injury Finder

I created a pitcher injury finder a while back but my computer died during a backup this past fall and I lost a ton of my programs. So, I recreated a basic program from what I remember of the previous inputs. I haven’t had a chance to run every test, so it’s a crude version but it’s at least up and running.

Its inputs, for now, are just fastball velocity, fastball spin rate, and Zone% with consistent release point to be added soon. I’d rather be a little off right now and keep adjusting the inputs than have nothing.

For the overall metric, a value of -100 means the pitcher’s traits point to worsening of his stats (e.g. velocity drop). A positive value means his traits are getting better (healthier).

With the season just getting underway, I’ll provide just information on the full 2017 and 2018 seasons. Later, I’ll look at just the past few days. Here is a list of the 20 pitchers who are most likely to be pitching injured and the 10 who show signs of being healthy (full list).

JC Ramirez is already done for the season after needing Tommy John surgery, but probably the biggest name on the injured list is Craig Kimbrel with a huge velocity drop.

While he still hasn’t allowed a run to score, his strikeouts are down and walks up in the small sample.