Josh Hejka
@hedgertronic.drivelinebaseball.com
Pitching @ PHI | R&D @ Driveline
A single outing contains a lot of noise but hopefully meaningful insights arise as the season progresses.
If you want to learn more about the PULSE metrics referenced above, check out the link below.
Stay tuned and follow along to see what we learn!
www.drivelinebaseball.com/2020/04/wha...
If you want to learn more about the PULSE metrics referenced above, check out the link below.
Stay tuned and follow along to see what we learn!
www.drivelinebaseball.com/2020/04/wha...
Using PULSE to define throwing workload | Driveline Baseball
Using Motus to calculate throwing workload in baseball. Acute to chronic workload ratios tell us about short and long-term arm health of players.
www.drivelinebaseball.com
March 10, 2025 at 9:03 PM
A single outing contains a lot of noise but hopefully meaningful insights arise as the season progresses.
If you want to learn more about the PULSE metrics referenced above, check out the link below.
Stay tuned and follow along to see what we learn!
www.drivelinebaseball.com/2020/04/wha...
If you want to learn more about the PULSE metrics referenced above, check out the link below.
Stay tuned and follow along to see what we learn!
www.drivelinebaseball.com/2020/04/wha...
What did my throwing look like today?
Recovery, recovery, recovery.
This is one of the easiest ways to keep up with the grind of a long season. Keeping the low days low helps keep the high days high.
Recovery, recovery, recovery.
This is one of the easiest ways to keep up with the grind of a long season. Keeping the low days low helps keep the high days high.
March 10, 2025 at 9:03 PM
What did my throwing look like today?
Recovery, recovery, recovery.
This is one of the easiest ways to keep up with the grind of a long season. Keeping the low days low helps keep the high days high.
Recovery, recovery, recovery.
This is one of the easiest ways to keep up with the grind of a long season. Keeping the low days low helps keep the high days high.
My chronic workload has lived in the 11-12 range over the last week. As I acclimate to the spring training schedule and prioritize my compete days, my ACWR has remained at or below 1.0.
After pitching yesterday, my CW was 12.1 and my ACWR was 0.98.
After pitching yesterday, my CW was 12.1 and my ACWR was 0.98.
March 10, 2025 at 9:03 PM
My chronic workload has lived in the 11-12 range over the last week. As I acclimate to the spring training schedule and prioritize my compete days, my ACWR has remained at or below 1.0.
After pitching yesterday, my CW was 12.1 and my ACWR was 0.98.
After pitching yesterday, my CW was 12.1 and my ACWR was 0.98.
As you may notice from the plot above, intensity seems to vary by pitch type. In this outing, my two fastballs had the highest torque on average and the slider had the lowest.
Interestingly, all pitch types had similar arm speeds. Good for deception perhaps?
Interestingly, all pitch types had similar arm speeds. Good for deception perhaps?
March 10, 2025 at 9:03 PM
As you may notice from the plot above, intensity seems to vary by pitch type. In this outing, my two fastballs had the highest torque on average and the slider had the lowest.
Interestingly, all pitch types had similar arm speeds. Good for deception perhaps?
Interestingly, all pitch types had similar arm speeds. Good for deception perhaps?
My throwing intensity (determined here as a % of the top 5 highest torque throws of the outing) was low pre-game and ramped up into my appearance.
During the season, when there is less certainty about when I will pitch, pre-game throwing becomes much trickier to manage.
During the season, when there is less certainty about when I will pitch, pre-game throwing becomes much trickier to manage.
March 10, 2025 at 9:03 PM
My throwing intensity (determined here as a % of the top 5 highest torque throws of the outing) was low pre-game and ramped up into my appearance.
During the season, when there is less certainty about when I will pitch, pre-game throwing becomes much trickier to manage.
During the season, when there is less certainty about when I will pitch, pre-game throwing becomes much trickier to manage.
On the throwing side, I made 80 total throws on the day for a total of 17.5 workload on PULSE. The vast majority of that workload came from my warmup and game pitches.
March 10, 2025 at 9:03 PM
On the throwing side, I made 80 total throws on the day for a total of 17.5 workload on PULSE. The vast majority of that workload came from my warmup and game pitches.
My WHOOP clocked me at 8:29 of sleep the night before the outing (and that's with the time change from daylight savings!).
Going to keep an eye on any potential correlations between sleep and velocity/performance as the year goes on.
Going to keep an eye on any potential correlations between sleep and velocity/performance as the year goes on.
March 10, 2025 at 9:03 PM
My WHOOP clocked me at 8:29 of sleep the night before the outing (and that's with the time change from daylight savings!).
Going to keep an eye on any potential correlations between sleep and velocity/performance as the year goes on.
Going to keep an eye on any potential correlations between sleep and velocity/performance as the year goes on.
According to Weather Underground's history feature, Clearwater was 79-80°F while I was pitching.
I'll be tracking this throughout the season to see how temperature affects in-game heart rate.
www.wunderground.com/history/dai...
I'll be tracking this throughout the season to see how temperature affects in-game heart rate.
www.wunderground.com/history/dai...
March 10, 2025 at 9:03 PM
According to Weather Underground's history feature, Clearwater was 79-80°F while I was pitching.
I'll be tracking this throughout the season to see how temperature affects in-game heart rate.
www.wunderground.com/history/dai...
I'll be tracking this throughout the season to see how temperature affects in-game heart rate.
www.wunderground.com/history/dai...
While not as consistently high as my big league spring training outing the other day (I guess the backfields ain't as stressful as the show), my heart rate still peaked at 178 bpm.
12:54: first pitch (157 bpm)
1:02: last pitch (178 bpm)
12:54: first pitch (157 bpm)
1:02: last pitch (178 bpm)
March 10, 2025 at 9:03 PM
While not as consistently high as my big league spring training outing the other day (I guess the backfields ain't as stressful as the show), my heart rate still peaked at 178 bpm.
12:54: first pitch (157 bpm)
1:02: last pitch (178 bpm)
12:54: first pitch (157 bpm)
1:02: last pitch (178 bpm)
This is amazing! Do you mind if I use it as my profile pic?
February 6, 2025 at 10:31 PM
This is amazing! Do you mind if I use it as my profile pic?
Does that chart you provided include both starters and relievers? Would be curious to see the trends for both separately.
January 30, 2025 at 11:36 PM
Does that chart you provided include both starters and relievers? Would be curious to see the trends for both separately.
Not 100% sure what’s happening here but a hypothesis is that a small velo gap is a proxy for fitness.
Being highly prepared for the demands of throwing means that you can throw harder for longer without getting fatigued.
Fatigue = lower velos AND fatigue = more injuries.
Being highly prepared for the demands of throwing means that you can throw harder for longer without getting fatigued.
Fatigue = lower velos AND fatigue = more injuries.
January 24, 2025 at 2:59 AM
Not 100% sure what’s happening here but a hypothesis is that a small velo gap is a proxy for fitness.
Being highly prepared for the demands of throwing means that you can throw harder for longer without getting fatigued.
Fatigue = lower velos AND fatigue = more injuries.
Being highly prepared for the demands of throwing means that you can throw harder for longer without getting fatigued.
Fatigue = lower velos AND fatigue = more injuries.
Are there general league-wide trends between day and night games?
A common thing I hear in the off-season is that pitchers feel like they throw slower early in the day but hitters may also feel that performance suffers.
Maybe can look at indoor games to isolate impact of time of day?
A common thing I hear in the off-season is that pitchers feel like they throw slower early in the day but hitters may also feel that performance suffers.
Maybe can look at indoor games to isolate impact of time of day?
January 11, 2025 at 7:36 PM
Are there general league-wide trends between day and night games?
A common thing I hear in the off-season is that pitchers feel like they throw slower early in the day but hitters may also feel that performance suffers.
Maybe can look at indoor games to isolate impact of time of day?
A common thing I hear in the off-season is that pitchers feel like they throw slower early in the day but hitters may also feel that performance suffers.
Maybe can look at indoor games to isolate impact of time of day?
Here’s @lambo.drivelinebaseball.com and @marekramilo.bsky.social’s presentation from saber sem introducing the concepts.
Ultimate goal is using these arsenal models to quantify batter familiarity and pitch buyback effects in order to optimize usage.
youtu.be/OdL6dafOArc?...
Ultimate goal is using these arsenal models to quantify batter familiarity and pitch buyback effects in order to optimize usage.
youtu.be/OdL6dafOArc?...
Quantifying Arsenal Effects A New Paradigm in Pitching Models
YouTube video by Driveline Baseball
youtu.be
January 7, 2025 at 9:34 PM
Here’s @lambo.drivelinebaseball.com and @marekramilo.bsky.social’s presentation from saber sem introducing the concepts.
Ultimate goal is using these arsenal models to quantify batter familiarity and pitch buyback effects in order to optimize usage.
youtu.be/OdL6dafOArc?...
Ultimate goal is using these arsenal models to quantify batter familiarity and pitch buyback effects in order to optimize usage.
youtu.be/OdL6dafOArc?...
Yes, this was one of the original goals we had in mind when we made Mix/Match but it requires getting Mix/Match in run value terms.
Would love to eventually have all independent models that can sum to the value of a pitch:
Stuff + Location + Mix/Match + Deception + … = Pitch Value
Would love to eventually have all independent models that can sum to the value of a pitch:
Stuff + Location + Mix/Match + Deception + … = Pitch Value
January 7, 2025 at 9:31 PM
Yes, this was one of the original goals we had in mind when we made Mix/Match but it requires getting Mix/Match in run value terms.
Would love to eventually have all independent models that can sum to the value of a pitch:
Stuff + Location + Mix/Match + Deception + … = Pitch Value
Would love to eventually have all independent models that can sum to the value of a pitch:
Stuff + Location + Mix/Match + Deception + … = Pitch Value
Is this based on component Stuff model or component Pitching model? I.e. do pitch locations factor into this?
November 29, 2024 at 8:38 PM
Is this based on component Stuff model or component Pitching model? I.e. do pitch locations factor into this?
Is this the same reasoning for why baseball WAR is split by a certain percentage batters vs. pitchers?
November 29, 2024 at 8:35 PM
Is this the same reasoning for why baseball WAR is split by a certain percentage batters vs. pitchers?
Accelerations for slower pitches live closer to the origin than the movement values for those same pitches.
In other words, movement is biased by time to plate (aka velocity) while accelerations aren’t.
In other words, movement is biased by time to plate (aka velocity) while accelerations aren’t.
November 26, 2024 at 10:23 PM
Accelerations for slower pitches live closer to the origin than the movement values for those same pitches.
In other words, movement is biased by time to plate (aka velocity) while accelerations aren’t.
In other words, movement is biased by time to plate (aka velocity) while accelerations aren’t.
Is there an easy way to tell from the MLB data if the roof was open or closed?
November 26, 2024 at 8:01 PM
Is there an easy way to tell from the MLB data if the roof was open or closed?
Awesome, glad it helped! Does it also increase the correlation when factoring in other layers on top?
Also, I'm not sure I fully understand what you mean by "average layer speed" of the batter. Do you mean the LANxwOBA value from this article?
tangotiger.com/index.php/si...
Also, I'm not sure I fully understand what you mean by "average layer speed" of the batter. Do you mean the LANxwOBA value from this article?
tangotiger.com/index.php/si...
Tangotiger Blog
tangotiger.com
November 25, 2024 at 12:15 AM
Awesome, glad it helped! Does it also increase the correlation when factoring in other layers on top?
Also, I'm not sure I fully understand what you mean by "average layer speed" of the batter. Do you mean the LANxwOBA value from this article?
tangotiger.com/index.php/si...
Also, I'm not sure I fully understand what you mean by "average layer speed" of the batter. Do you mean the LANxwOBA value from this article?
tangotiger.com/index.php/si...
Do you think there’s any value in adjusting for the max EV of the batter faced?
E.g. assume there are two BIPs at 95 mph EV, one against a batter with 100 mph max EV and another against Giancarlo Stanton. Wouldn’t each tell me different things about the expected future EV allowed by the pitcher?
E.g. assume there are two BIPs at 95 mph EV, one against a batter with 100 mph max EV and another against Giancarlo Stanton. Wouldn’t each tell me different things about the expected future EV allowed by the pitcher?
November 24, 2024 at 4:31 PM
Do you think there’s any value in adjusting for the max EV of the batter faced?
E.g. assume there are two BIPs at 95 mph EV, one against a batter with 100 mph max EV and another against Giancarlo Stanton. Wouldn’t each tell me different things about the expected future EV allowed by the pitcher?
E.g. assume there are two BIPs at 95 mph EV, one against a batter with 100 mph max EV and another against Giancarlo Stanton. Wouldn’t each tell me different things about the expected future EV allowed by the pitcher?
Might be too complicated for a single plot but could be interesting to see how arm angle differs by pitch type.
November 23, 2024 at 7:01 PM
Might be too complicated for a single plot but could be interesting to see how arm angle differs by pitch type.