The stint of time that a player has to spend on the injured list is returning to 15 days for the 2022 season, per reports. Since the 2017 season, the injured list had been 10 days, but under the new CBA it appears that the 15 day injured list is returning.
In addition, players that are sent down on an optional assignment must now spend at least 15 days in the minors before being recalled, rather than 10 days.
These changes, along with the new rule limiting the number of times a player can be optioned in one season to five times, are presumably motivated by a desire to reduce roster churn. Teams with more depth could bounce players up and down between the majors and minors, or stash players on the injured list for short stints, in an effort to effectively allow them to work with a larger roster.
The biggest impact was in the way bullpens, and pitching staffs in general, have been managed, allowing teams to go with more max-effort guys for short stints, since they could shuffle the roster as needed to get fresh arms in the pen as needed. MLB is also implementing a cap on the number of pitchers a team can have on its active roster — 13 — which was supposed to go into place for the 2020 season, but which was tabled due to the COVID-19 pandemic.
These rules are likely going to place a premium on having pitchers who can provide length and multiple innings, rather than just loading up on hard-throwing one inning guys.