Postseason debuts side-effect of 2020 roster churn, off-day-less October

Prior to 2020, only two players had ever made their major league debuts in the postseason.

In 2006, the Athletics found themselves in a dire situation after losing a handful of infielders to injury, capped by Mark Ellis breaking his right index finger after swinging at a pitch that hit his hand. Mark Kiger, then, was added to the playoff roster, and on October 13, he made his debut as a defensive replacement in Game Three of the ALCS. Though he also appeared as a substitute on defense in Game Four, Kiger never recorded a postseason plate appearance, and was released by the A’s shortly after the season ended. Because he never returned to the majors, Kiger is the only player in baseball history to play his entire major league career in the postseason.

Nine years later, in 2015, Adalberto Mondesi became the first player in baseball history to make his debut in the World Series. No injury necessitated the move; Kansas City simply added him to the roster to replace Terrance Gore. The utility of the switch was understandable, too. With Games Three, Four, and Five all taking place at Citi Field, Mondesi could serve as a more effective pinch hitter than Gore, who mostly came in to run the bases. Indeed, in Game Three, Mondesi debuted as pinch hitter for Danny Duffy, and fell victim to the Noah Syndergaard strikeout.

These two cases — Kiger and Mondesi — seemed like one-offs. In the case of Kiger, a host of injuries created the unique situation. For Mondesi, it was more roster construction. No trend in sight here.

This year, however, we’ve seen something completely different. Here’s what happened:

Turning this into a chart is a little extra, I’ll admit, but it does underscore the point. In the World Series Era, going all the way back to 1903, there was not a single postseason debut for more than 100 years. Then, in 2006 and 2015, there were one-offs. Now, in 2020, there have been three more, bringing our grand total from two postseason debuts all the way up to five.

This uptick started when the Twins promoted Alex Kirilloff ahead of their American League Wild Card series. In Game Two, the team’s No. 3 prospect, per FanGraphs, made his debut, starting in right field and hitting sixth. In the fourth inning, Kirilloff recorded his first major league hit, becoming the first to do so in the postseason. He also made a sliding catch in right field. Though the Twins were eventually eliminated that day, Kirilloff seemingly set the tone for the postseason in a different way.

Five days later, Rays lefty Shane McClanahan became the first ever pitcher to debut in the postseason, allowing a single and a walk before recording the last out of the top of the ninth, a low leverage spot with Tampa Bay down 9-3. The very next day, Padres lefty Ryan Weathers — who had never pitched above Single-A (!!!) — did the same thing, assisting in the relief effort after Mike Clevinger exited Game One due to injury. Baseball Twitter gawked at the numbers put up on screen when he came in to pitch in the third:

Yes, that’s a 0.09 ERA. He allowed one earned run over 76 innings in seven-inning games. Weathers struck out the first batter he faced, Mookie Betts, and generally made quick work of the Dodgers overall, pitching 1 ¹⁄₃ innings, allowing no runs and no hits, striking out two and walking just one.

All of these postseason debuts are indicative of two unique features to 2020: more roster churn and no October off-days.

The increased number of debuts in 2020 is not unique to the postseason. According to research done by Jon Becker, who tracked major league debuts going back to 1998, 2020 has the most debuts per 2,430 games by a wide margin:

Even before this year, there’s a clear trend: major league debuts were becoming more common. It wasn’t too noticeable — we were only averaging about three additional debuts per 2,430 games — but the trend was there:

Things exploded this season for a combination of reasons. COVID-19 threw a lot of uncertainty into the mix — the Marlins, for example, returned from their COVID-19 outbreak cancellations with 17 new players on their 30-man roster, seven of whom had yet to appear in the majors. More generally, though, expanded rosters, which never fell below 28 at any point during the season, also contributed, as did opt-outs and injuries likely related to the layoff between spring training and summer camp.

Additionally, teams cited the alternate sites — put in place of the minor league season, which was cancelled this year — as another reason for the rapid rate of call-ups.

“Major league coaches and front office people were able to go over and watch him play and watch him develop,” Twins GM Thad Levine told Yahoo Sports’ Hannah Keyser about the promotion of Kirilloff. “Where normally, you’re relying on minor league staffers exclusively and scouts — obviously we trust those groups — but it’s even more magnified, I think, when major league coaching staff members and/or major league front office people are able to lay eyes on a player.”

Not only were teams able to have a closer look at their prospects, but they were also able to control their level of preparation. Padres GM A.J. Preller told Keyser that the organization was able to “challenge [Weathers] with some different roles” ahead of his postseason promotion, giving the team more confidence that he would be ready for San Diego’s short-term October needs.

That, plus the lack of off-days within postseason series, extended the trend into October. Though it’s impossible to know for sure, McClanahan probably wouldn’t have pitched in a normal postseason. But because the Rays will have had five consecutive days with a game against the Yankees, him recording the last out of the ninth might’ve saved a few pitches from someone else.

That’s not to say that the lack of off-days is necessarily a good thing for postseason baseball; it isn’t. But what it has done is given us yet another unique wrinkle for 2020. After not seeing a postseason debut for over 100 years, then seeing two more-or-less out of necessity, baseball in 2020 has given three more players the opportunity to play in the majors. These debuts just happen to be in games and series where the stakes are the highest.

Devan Fink is a sophomore at Dartmouth College and a Contributor at Beyond The Box Score. Previous work of his can be found at FanGraphs and his own personal blog, Cover Those Bases. You can follow him on Twitter @DevanFink.