The 5-game ALDS series roster formation is the question here. Rosters are reformulated after each series. A roster vs the Astros may be tailored differently than vs the Yankees.
Some teams run with three starters in a 5-game series and some continue with it throughout the post-season. In '87 and '91, they had Viola, Blyleven, and Straker; and Morris, Tapani, and Erickson pitching on three days rest in each series.Last season in the playoffs, the only teams using a pitcher or pitchers with 3-days rest were the Braves in the NLDS and the Brewers in the NLCS. Both clubs were eliminated. The '19 Twins starting staff isn't set for that. Barring injury, it's pretty much a lock the Twins will roster four set starters.
Last season, the eight teams in the divisional series' went three different routes, with 11, 12, or 13 man pitching staffs.
Barring an injury to a rostered player, Graterol won't be eligible for the post-season if he isn't added to the 40-man roster by midnight on Saturday. With the one open spot lingering, it makes me wonder if the team is still weighing options on post-season scenarios. Graterol, Alcala, Gordon, Miller?
Anyway, while I love the speculation here, the reality a month from now will tell the tale. Cave would seem like a lock if the playoffs started tomorrow; not a lock in October. The fate of a few relievers could hinge on how well they're throwing at the end of September. The team can roll the dice on a hot hand for a 5-game roster.
As for Schoop being a near lock because he's played so much, it isn't written in stone. 30-game starter Chase Anderson was left off the Brewers roster last October. In 2016, the Cubs dropped 15-game winner Jason Hammel and Joe Szczur, and Tommy La Stella was left off the NLCS roster. That's off the top of my head.