The Z Files: Five Is the New Four

It's become cliche, but managers say they love a starter who can "take the ball every fifth day." Pitchers say, "I want the ball every fifth day."

Twenty years ago, this was the norm. More than half of all starters went with four days of rest.

For fun, check out the data from 50 years ago.

What about last season?

That's right, more starts occurred with five days of rest than four. This is partially, but not completely, due to adding some off days to the schedule. Here is data from the past five full seasons.

Keep in mind the lockout condensed the schedule in 2022, accounting for the higher percentage of four days of rest. Otherwise, there would be a trend towards more starts with five days of rest.

Here is the complete rundown from last season.

The total falls short of the 4860 games started because each pitcher's first start doesn't register.

Here is a look at the aggregate performance for each time frame.

The narrative would have been better if the improvement with five days of rest was greater, but there are slightly better results as compared to four days of rest.

Cole Ragans, with a dash of Michael King, are the reasons I went down this rabbit hole. Both emerged from the bullpen to turn heads as starters. In the process of evaluating each, I was curious how much rest each received between starts. If they were afforded extra rest, perhaps their performance would suffer if they worked with less rest between starts. Here is data for each.

The elegance of this discussion is there is no right answer. If you're a Ragans stan, you'll brush off the fact he pitched mostly on more than four days of rest. Some may even cite the following splits and contend Ragans will thrive with less rest.

Clearly, this is myopic as the samples are too small to draw such a conclusion. 

Personally, I am more concerned about Ragans being able to repeat the ridiculous skills level he showed than I am about the rest issue, but sure, it is a concern. That said, analysts specializing in pitch modeling are enthralled by Ragan's stuff.

I'm guessing you're now curious about the workload distribution of other starters. Ask and ye shall receive. After the table, some other intriguing hurlers will be highlighted. Again, there isn't a definitive word of warning or "no big deal" for anyone. It's just some (hopefully) intriguing information to consider when making decisions.

Observations

Only six of Corbin Burnes 31 starts occurred with four days of rest. It will be interesting to track if the Orioles are aware of this and treat their ace in the same manner as the Brewers. One hint: 10 of Kyle Bradish's 29 starts happened on four days of rest, so perhaps they won't force Burnes onto an every fifth day schedule.

Perhaps because they didn't trust the back of the rotation, three Diamondbacks starters worked mostly on four days of rest. They are Zac Gallen, Merrill Kelly and Ryne Nelson. Keep in mind that making the World Series extended the workload of Gallen and Kelly. If they continue to be pushed, their performance may suffer. It's just speculation, but sometimes details of this nature can be used to break a tie in a coin-flip scenario.

The Twins often gave their starters five days of rest. Perhaps this was because they weren't pressured to shorten the rotation due to being in a close race for a playoff berth. Sonny Gray, Pablo Lopez, Joe Ryan and Bailey Ober all started at least six more games on five days of rest than they did with four. Maybe this is why Gray and Lopez avoided the IL. They both have experienced health issues. It's important to note Gray and Lopez collected 32 starts each, so the extra rest didn't affect their overall workload.

Only eight of Spencer Strider's 31 outings were with four days of rest. He enjoyed five days between efforts on 19 occasions, while he pitched on six days of rest four times. This suggests Atlanta is mindful of their ace's health, which adds comfort to those paying top dollar for one of the top-two fantasy hurlers.

Only 17 pitchers started a minimum of 20 games with at least five more starts on four days of rest than they got on five days rest. Four of them were Cubs: Jameson Taillon, Marcus Stroman, Drew Smyly and Justin Steele. Of course, the club has a new manager, with Craig Counsell replacing David Ross. Counsell was with the Brewers last season. Corbin Burnes led the league with 23 starts on five days of rest. Freddy Peralta started six times on four days and 19 with five. Only two of Wade Miley's 22 starts occurred with four days of rest. There is no guarantee Counsell handles the Cubs rotation like he did the Brewers, but it seems likely. It's conjecture, but this could help Justin Steele, adding a layer of confidence when clicking him onto your roster.

Unsurprisingly, the Angels staff started the fewest games on four days of rest. Call it the Shohei Ohtani effect. With Ohtani rehabbing from Tommy John in between clubbing homers across town, Reid Detmers, Griffin Canning, Chase Silseth and Patrick Sandoval will all likely pitch with just four days of rest this season. They're all breakout candidates but have injury or performance concerns. Working with less rest isn't enough for me to avoid any of them, but how they respond (with sample size caveats) is something to track. My leash for this quartet may be a bit shorter if their velocity is down, or stuff isn't as crisp.

I have a feeling I'm going to be referring to the usage table a lot this season, particularly for the Weekly Pitching Rankings. Hopefully you'll bookmark it too and visit it on occasion.