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Everything to Know About MLB's New Rules in 2020

MLB will see some noticeable changes in 2020. Here's what you need to know about each of the rule adjustments.

Back in March, MLB announced a set of new rules to be rolled out across 2019 and 2020. There wasn’t too much to watch in the ones rolled out this past season—what, you weren’t monitoring the drop in mound visits?—but there’s some meatier stuff on deck for 2020. So what do you have to watch out for, and what could it mean for teams’ needs this offseason? Here’s what you need to know, rule by rule:

New Rule: The active roster size with increase from 25 players to 26. Then, in September, the roster will expand up to 28, rather than 40.

How Much It Will Matter: Not a whole ton. Of course, there’s value in an extra man, but it’s hard to envision this bringing any particular shift in strategy or roster construction—especially since teams already have so much movement with shuttling guys between Triple A and the Show, and on and off the 10-day IL, that any “26th man” likely already had decent playing time. As for the difference in September, it should cut down on the worst offenders when it comes to crazy ‘pen parades (and, sadly, the best ones when it comes to minor-league lifers finally getting their chance in the big leagues) but that shouldn’t be felt particularly hard, either, as most teams’ September rosters already sat closer to 28 than 40.

What To Watch Out For: What will we be able to learn from how teams allocate that spot? Who goes for an extra bat, versus a defensive specialist, versus a third catcher? (If your guess was “extra reliever”… more on the new pitching rules in a moment!) Will there be a consensus trend? Or will we see a bit of everything?


New Rule: Teams must label each one of their roster spots as pitcher, position player, or two-way player. (A “two-way player” must have a record of one season with at least 20 IP and 20 games started with three plate appearances or more as a position player or designated hitter.) There will be a limit on the total number of pitchers per roster—probably 13, but this part is not official yet—and position players will not be able to pitch unless a game has a run differential of more than six or is in extra innings.

How Much It Will Matter: In terms of immediate direct effect? Not that much. Yes, the last few years have seen an increase in both the number of two-way players and the number of position players pitching. But this rule doesn’t necessarily prevent any of that. The two-way players that are serious two-way players—Shohei Ohtani, Brendan McKay—should be able to continue as such. And position players will still be able to pitch in almost all of the scenarios in which they currently pitch. 

It’s true that the uptick in the last few years here has been big: 26 games with position players pitching in 2016 versus a record 90 in 2019. But that’s come almost largely in games that would be permissible under the new rule (i.e., in extra innings or with a run differential of more than six). From last year, 86 of those 90 would still be allowed in 2020. (The four that would have been blocked had a run differential of either five or six.) So the number of position players pitching may not continue to skyrocket, but it probably won’t drop too much, either.

Source: Baseball-Reference; Ohtani and McKay excluded.

Source: Baseball-Reference; Ohtani and McKay excluded.

And in terms of using these player classifications to set the maximum number of pitchers per roster at 13… that, too, should have only a small impact. It’s only in the last few years that we’ve had to process the idea of teams using a 13-pitcher, 25-man roster, and it’s hard to picture clubs trying to realistically push beyond that while still having, you know, a bench. This isn’t pushing teams backward. It’s just setting a formal limit where they already are.

What To Watch Out For: The two-way players that you think of as two-way players won’t be touched. But what about fringe-y cases? Remember San Diego’s Christian Bethancourt experiment from 2017? Last winter’s talk about Matt Davidson? There’s been a recent trend toward trying to cultivate two-way players, whether to maximize individual value or simply boost roster flexibility. (The Angels alone have several of these guys in their system: Jared Walsh and William English, plus Kaleb Cowart.) But now that there are set minimums for these players—20 innings and 20 games started in the field or at DH—maybe that will shift a little. 

This is not the end of two-way players. But it may cause a shift in teams’ willingness to experiment with guys in the minors if they’re not sure they’ll be able to use them to their full potential in the majors.


New Rule: A pitcher must either face at least three batters or pitch to the end of the half-inning.

How Much It Will Matter: Yes, this has been labeled the “three-batter minimum.” No, it’s actually not that big of a deal. The “or pitch to the end of the half-inning” does a lot of work in this rule. As Mike Petriello spelled out over at back when this rule was announced, most short relief appearances—two or fewer batters—are set up to end a half-inning. Those aren’t affected by this. There are short relief appearances that don’t go to the end of a half-inning, but they’re far less common, and getting rid of those is more likely to be felt as “cutting down on time-consuming mid-inning pitching moves” versus “removing brilliant strategy.” As for what this means for the LOOGY? Don’t worry—they were dying, anyway. (The LOOGYs themselves, of course, feel differently.)

What To Watch Out For: This, on its own, probably would not create a dramatic shift in ‘pen construction. But throw it in with rosters’ new limits on pitchers… September expanded rosters that provide less relief than ever… the existing trends toward super relievers… it’s really hard for a specialist out there, such that they still are, and this rule only makes it even harder.


New Rule: The minimum time on the injured list for pitchers will increase from 10 days to 15 days. (The 10-day IL will still exist for position players.)

How Much It Will Matter: The 10-day IL meant that—with proper back-dating and rotation shuffling—it was possible for pitchers to miss just one start while going off the active roster to rest up with a minor injury. Not so much now. This makes it trickier to game the system. It’s hard to say just how many phantom injuries there have been since baseball moved from a 15-day IL to a 10-day in 2017, but however many it is, there should be fewer going forward.

What To Watch Out For: It’s hard to think of just how this rule can be worked around… but if there is a way, trust that Andrew Friedman and the Dodgers will find it.