Operating under the assumption that the regular season will be shortened, every game will carry increased importance for making the post season. This creates competing motivations for teams. They want to get their top pitchers going as quickly as possible to be competitive but ramping up too quickly could force time on the IL and cause more time to be missed compared to shortened or skipped appearances early on.
As teams try to return to normal operations following the coronavirus shutdown ensuring player safety needs to be a point of emphasis. The loss of oversight and management of workload during Spring Training especially puts pitchers as risk, similar to the risk they are exposed to leading up to and during the first weeks of Spring Training. The graphic below shows a projected workload increase for a pitcher followed by the loss in chronic workload they would experience if they don’t continue throwing after the shutdown. I would expect players to keep throwing in some capacity, however, a player could just as easily go the other direction and overload themselves leading to injury during the shutdown. Teams are somewhat in the dark on how much and how often each player is throwing during this time and the injury risk associated with those choices leading into the season.
Ideal Workload Monitoring
The ideal process would be to issue each pitcher a Motus sleeve and sensor and have them collect their own workload data. Teams could see this data and help scale workouts remotely creating an “at-home Spring Training”. Based on my experience at Motus, there are limited teams who have the capacity to do this. There aren’t enough sensors for everyone, players don’t know how to collect and download data accurately, and the organizational infrastructure doesn’t exist to manage a project like this on such short notice.
Fortunately, there is a way teams could estimate workload and help ensure pitchers aren’t being exposed to more workload than they can handle. I will outline that method, walk through an example, and point out the challenges/shortcomings it presents to teams.
Workload can be estimated using throw counts and the specific player’s average torque measurement. This means all a pitcher needs to do for the organization is count their throws each day and record them. A bonus would be to break the counts by low and high intent so two different torques could be used and weighted.
I would tell players to classify throws using this guide:
Low Intent – warmup/cool down and long toss expansion under 120 feet
High Intent – long toss over 120 feet and bullpens
Important Note: Throw Counts are NOT the same as Pitch Counts. Every throw needs to be included in a workload calculation for it to provide value. Brian Goelz summarizes the importance of this difference best in a recent blog post he did for Driveline “every throw counts and not all throws are equal.” Warmup, expansion during long toss, and cool down throws are just as important to workload as bullpen sessions. This is also why breaking up throw counts by intent adds value to the estimation.
For this method I am assuming the player has not used a Motus sleeve lately and their workloads (acute and chronic) are not being tracked. If those assumptions are false, this process can be much more accurate and daily throw volumes can be projected and adjusted in real time for the player since testing after the shutdown won't be needed. I will not go through this process because I don’t believe there are many teams in this situation.
There are three steps to calculating workload values using the estimation method:
1) Estimate acute and chronic workloads before the shutdown using the player’s throwing schedule. (Same as Step 2 but using team throw counts/estimates)
2) Calculate daily workload values using player reported throw counts and average torque measurements.
3) Calculate current acute and chronic workloads and identify any need for additional on ramping and any injury risk exposure from spikes in ACR during the shutdown
Once these steps are complete a team will have an estimation of where each player stands and where they need to be allowing for proper workload management and mitigation of injury risk.
For reference before starting an example, here are the target values for a healthy starting pitcher on Opening Day:
Chronic Workload – 15 to 20
Acute/Chronic Workload (ACR) – 1.0 to 1.3
Example (All Throw Data Estimated)
Step 1 -
The player’s workloads prior to March 12 when the shutdown began are estimated using the organization's throwing protocols and league average torque values. These estimates can be updated once torque values for the player are collected after the shutdown ends. The table below shows where the example player stood on March 12.
Step 2 -
The player reports throw counts shown in the table and plot below:
Upon return and use of a Motus sleeve, the following average torques are measured for the player and converted to a coefficient using Motus’ formula which normalized for height and weight:
Using these tables, the daily workloads shown in the table and plot below can be calculated using the following equation:
DailyWL = 0.16*Low_Intensity_Throws + 0.27*High_Intensity_Throws
Step 3 -
Daily Workloads are used to create rolling weighted averages for Acute (7-days) and Chronic (28-days) Workloads. The table below shows each metric starting on March 13 but these values use the estimates from all of Spring Training as well.
The plot below shows the player’s Chronic Workload and ACR throughout the spring with the shutdown period shaded grey.
Assessing Workload and Injury Risk
The player did a good job managing ACR but was not aggressive enough in building Chronic Workload without team oversight. He ended the shutdown with an ACR of 1.09 and a Chronic Workload of 13.62. He maintained a safe on ramping pace (no ACR spikes above 1.3) but is behind schedule for Opening Day. In this case it would be best to continue projecting ACR and Chronic workload to determine how often and how long the player can throw until his Chronic workload is at least 15.
I projected forward being as aggressive as possible and without exceeding an ACR of 1.3 and the player was ready for a "full" start on May 28, 18 days after my projected end to the shutdown. This may be about when competitive baseball begins but that projection relies on no setbacks during a period of fairly intense training.
The main shortcoming of this method is that the team is relying on players to count throws accurately and to “tag” them as low and high intent correctly. The reason wearing a Motus sleeve for all throws is so useful is because it measures each throw individually and the intent is continuous instead of using the bins and averages discussed. The workload estimates from during Spring Training are also subject to error unless teams to an exceptional job counting each player's throws.
Additionally, the lack of estimation until after the shutdown ends exposes pitchers to high risk during the shutdown. Under ideal circumstances, and use of a Motus sleeve, an accidental day of overwork could be addressed with extra rest, but in this case the player won’t know if they have pushed too hard outside of the normal gages like soreness or injury. This method only allows teams to reactively address workload mismanagement instead of proactively tracking and adjusting.
Teams are now in a position where the risk of injury to their pitchers is elevated. Additionally, the specific risk for each player is unknown due to the lack of workload oversight during the shutdown period. Using a single Motus sleeve collection session and player reported throw counts broken down by low and high intent, teams can estimate a pitcher’s Chronic Workload and ACR allowing for adjusted management during the early weeks of the season. By implementing this process, a team may lose length or quantity of appearances a pitcher makes early in the season, but prevent extended IL stints or catastrophic injuries to their pitching staff ultimately increasing their chance of success in 2020.