What happened: Boston's likely postseason bullpen starts with Aroldis Chapman closing and Garrett Whitlock, Erik Miller and Tyron Guerrero in leverage spots, while Garrett Crochet's return and Justin Slaten's forearm issue complicate the final relief mix. Assuming health, the projected rotation for October is Ranger Suarez, Sonny Gray, Payton Tolle and Jake Bennett, leaving the club to sort through a 13-man pitching staff and nine reliever spots.
Why it matters: That pecking order matters for a Boston club that was 10-17 in late April and has since climbed into the American League's fifth seed. A shorter opening series can trim the staff, but deeper October rounds put more weight on left-right matchup coverage and late-inning depth, which is why Crochet's availability and Slaten's status carry so much weight.
By the numbers: Chapman has 34 saves with a 1.95 ERA in 50 2/3 innings. Whitlock has a 1.81 ERA, 0.83 WHIP and a 27.4% K-BB rate, a mark topped only by Mason Miller, Jacob Misiorowski, Jhoan Duran, Josh Hader and Mason Montgomery among pitchers with at least 40 innings. Lefties are batting .173 with a .247 slugging percentage against Erik Miller, while Guerrero has cut his walk rate to 4.4% this season.
What to watch: The next clue is whether Crochet gets back into a game before the postseason, with a possible final-weekend window against the Cubs. Boston also has to decide whether Slaten can be counted on for one of the last relief spots.