Before the season started, we took a look at a stat called Work Number, which tries to identify which pitchers may be "overworked" and, as a result, potentially in line for fewer innings pitched as the season trudges on towards October. In the worst-case scenarios, these tend to be the guys at the most risk for serious injury, and we recommended proceeding with caution when it came to drafting these arms.
Now that we're closing in on the halfway point of the 2021 season, we have a solid enough sample size of starting pitcher outings to take a closer look and see which hurlers might want to be bubble-wrapped and stamped "Handle with Care" for the rest of the way, and which ones should still have plenty of steam left come September's stretch drive.
As a reminder, Work Number is based on the work of sabermetrics legend Tom Tango, who has done a ton of research into figuring out the expected number of pitches a pitcher "should have thrown," based on their innings pitched, strikeouts, walks and hits allowed. Given this solid formula for predicting an expected number of pitches based on actual game outcomes, any variance between that number and the actual pitch count is likely the result of a pitcher working harder than he needs to.
In fairness, all starters have occasional innings (and even full outings) where they work too hard compared to what they "should have" done. However, most of the time over the course of a full season, those instances tend to be balanced out by those innings and games where they cruise in terms of pitch count compared to the expected workload, given the outcome.
Where red flags should definitely be raised for fantasy managers are those cases where a pitcher is consistently throwing "too many pitches." Over the course of the season, those extra pitches tend to add up and result in tired arms over the latter parts of the campaign -- meaning shorter outings, missed turns in the rotation, and even stints on the IL.
In March, we had listed the pitchers who had gone through 2020's abbreviated campaign with the highest Work Number and warned that these starters were more at risk to get injured early in 2021, with that risk only increasing if their Work Number remained high as the new season got into full swing.
Some of the names on that watch list, like Johnny Cueto and Brandon Woodruff, were able to significantly lower their Work Number over the first half of 2021, and both have seen improvement year-over-year statistically as well as a result.
Then there's Matthew Boyd, Jacob deGrom, and Max Scherzer. Boyd came out of his last start on June 14 and was diagnosed with tendinitis and inflammation in his throwing arm. He will not pitch again until at least after the All-Star break. Scherzer just came off the IL yesterday after tweaking a groin muscle and while that doesn't seem anywhere near as serious as an arm injury, issues with being overworked can take many different forms.
I think deGrom has suffered from every single one of those forms having now being pulled from multiple games due to one incident of shoulder tightness, another of shoulder "discomfort" and an instance of flexor tendinitis. Now, the Mets ace has claimed that his problems have primarily stemmed from swinging the bat and not actually from pitching -- and indeed, his Work Number for 2021 is an amazing minus-72.4. Still, one can't help but wonder if things might be a whole lot worse if this year's Work Number was not as stellar as it has been.
We continue to be concerned with Lance Lynn, Dylan Cease and Trevor Bauer, all of whom had Work Numbers over 50 in 2020 and continue to throw far more pitches than truly necessary in 2021. After all, pitchers who have a high Work Number during a given season are more at risk to get injured during that season and that's only compounded when that overwork continues year after year.
Here's the list (through Monday's games, minimum 50 IP) of the most taxed hurlers thus far:
Each of the above pitchers should be watched very carefully and perhaps traded away in fantasy if you can get good value for them now -- before the bottom falls out. Jack Flaherty and Madison Bumgarner are already attempting to get healthy and are currently on the IL. Meanwhile, Jameson Taillon's first season back after Tommy John surgery is certainly not going as smoothly as one would like. You should also note that the Chicago White Sox are very represented on this list, which does not bode well for that staff at all. In fact, if you look at the splits, as a rotation, Chicago's ERA has risen from 2.85 in May (5.7 IP per start) to 3.82 (5.6 IP per start).
Meanwhile, at the other end of the spectrum, here's a list of those pitchers who would seem to be handling their business as efficiently as possible this season:
Now, this doesn't mean that these pitchers can't still get hurt (the presence of deGrom and Shane Bieber here prove that), but seeing the likes of Shohei Ohtani, Trevor Rogers and Julio Urias in this grouping is still preferable to the alternative. This doesn't mean clubs won't still end up shutting these guys down due to a pre-determined innings cap -- especially with this trio. That's a different form of measuring workload (as my colleague Tristan H. Cockcroft so excellently addressed here). Still, when it comes to figuring out which pitchers you might want to send packing before their 2021 expiration date sneaks up on you, the Work Number should certainly play a part in your decision-making process.