Major League Baseball released their latest massive update to the publicly available Statcast data, introducing bat-tracking data this week. For an intro to the concept, check out this primer from Mike Petriello of MLB.com.
I’ll be digging into these numbers a lot over the next few weeks, as I’ve been waiting for this update. Over the last few years I’ve upgraded my own understanding of hitting, after seeing that as a weak point of my scouting abilities. These numbers add to that knowledge base, while allowing me to convey my existing knowledge.
Before I dive into the Pirates numbers, I want to give my own look at some of the concepts.
THE NEW METRICS
The new data brings us new metrics to evaluate every hitter. Here are the explanations of those metrics.
Avg. Bat Speed – The new metrics track how fast a player swings, per the average of his top 90% of swings. To get a good measuring point for average bat speed, most home runs are hit with a bat speed of 75 MPH or harder.
Fast Swing% – This is how often a player has a swing of 75 MPH or harder.
Number of Squared Up Swings – “Squared Up” means that a swing achieved at least 80% of the maximum possible exit velocity based on the swing speed and speed of the pitch.
Squared Up/Contact – A metric measuring how often a player squares up a pitch by how often he makes contact. There is also…
Squared Up/Swing – I like this metric more than the contact division. The contact metric measures the ratio between two outcomes. This metric measures the ratio between an outcome (squared up) and an actionable decision (swing). Thus, we get to see how often a player’s decision to swing ended up with desirable squared up contact.
Number of Blasts – A blast measures hard swings and contact efficiency. It can be measured as percent squared up*100 + bat speed >= 164. For example, if you square up a pitch at an 84% rate, you would need a bat speed of 80 MPH or higher to get a blast.
Blasts/Contact – Again, this stat gets measured by contact and swing. I do like the “Outcome/Outcome” metric here, as it measures a rate of successful hard contact out of all of a player’s contact. The fact that blasts already include squared up in the equation makes this stronger than Squared Up/Contact.
Blasts/Swing – I still prefer the “Outcome/Action” ratio here.
Swing Length – This tracks the distance traveled by the head of the bat in the XYZ space from the start of the swing until contact point. I’ll get to this in the next section.
Swords – These are uncomfotable, awkward swings.
THE SIZE OF THE HITTER
The size of a hitter is going to impact swing length and speed. Take the Statcast given comparison of Giancarlo Stanton and Luis Arraez.
This is interesting. Consider that swing length might not be a skill but representation of a physicality.
Stanton is 6'6" with longer limbs. Arraez is 5'10" with shorter limbs.
If their bat speeds are equal, then Arraez can start his swing later to make contact at the same… https://t.co/16Yw7YvoIE
— Tim Williams (@TimWilliamsP2) May 14, 2024
Stanton has a 9.7 foot swing path, but it comes from a 6′ 6″ frame. Arraez is 5′ 10″, and his swing is 4.4 feet, or less than half of Stanton’s. Stanton has the advantage of longer limbs and thus, a longer swing path. If they both start with the same acceleration rate, Stanton would have more room for his bat to gain velocity along his swing path.
Arraez has an average bat speed of 62 MPH, while Stanton leads the league at 81 MPH.
Part of these metrics are things that can’t be controlled. I don’t think a longer swing speed should be valued, nor should a shorter swing speed be punished, as they can merely reflect on a player’s size. This does quantify the advantage that larger players have, but it also shows how smaller players can be successful.
In the case of Arraez, he leads the league in squaring up pitches. So while he doesn’t have the fastest bat speed, which won’t get him many blasts, he does have a very accurate bat. He also can start his swing later, with a shorter path to travel. This gives him more time to analyze what pitch he’s swinging at, compared to Stanton, who would need to begin his swing earlier at the same acceleration rate.
I liken this to a vinyl record.
I think of this like a vinyl record.
Records spin at an accelerating rate of 33.3, 45, or 78 RPMs. However, the outside and inside of a vinyl travel at different speeds to end up making the exact same 360-degree revolution at the same time.
Stanton is the outside of a vinyl and… pic.twitter.com/YjXq13IhcY
— Tim Williams (@TimWilliamsP2) May 14, 2024
If you draw two points on a vinyl record — one on the inside grooves and one in the same line on the outside grooves — both of those points will make a 360-degree rotation at the same rate. However, the path for the inside of the record is shorter around the turntable. Every time you spin a vinyl record on a turntable, the outside of the record is traveling at a speed much greater than the inside of the record. The acceleration rate for both is going to be the same, set by the turntable, dependent on the record speed (33.3, 45, or 78 RPMs).
We don’t have acceleration data for hitters (though that would be an easy metric to figure out), but if the acceleration for Arraez and Stanton are the same, then Arraez is on the inside of a record and Stanton is on the outside. They can both get to the same point at the same time, just with different paths.
In terms of data contained on the record, the inside of a record is more compressed with information, while the outside has more room for audio quality. On the same note with hitters, Arraez needs to do more with his decision making on the inside of the swing record, while Stanton has more room in his swing on the outside of the record for more quality beats.
THE PIRATES HAVE A TALL HITTER
Oneil Cruz doesn’t have the longest swing length on the Pirates, but he does have the highest average bat speed at 77.9 MPH. He also has the highest fast swing% at 74.9%. Cruz benefits from his size, but there are other factors to consider than just physical attributes.
