Cory Abbott, Tyler Thomas, and Rollie Lacy are the three most obvious candidates from the South Bend staff. They are experienced college arms taken in the 2017 draft and have dominated Midwest League hitters for most of the season. The only thing they have not done is go deep into ball games, but that may be by design. These players are transitioning to pro ball, where they are now expected to go every five days instead of once per week, and the season is far longer. It is probably a solid strategy to keep their arms fresh throughout the course of the season, instead of worrying about shutting them down before the season ends as they reach an innings limit. Thomas Hatch was similarly handled throughout much of last season, but they are now allowing him greater freedom.
I would expect 20-year old Javier Assad, as well as Brendon Little and Erich Uelmen to remain in South Bend throughout the season. These pitchers are more long term projects and having them take their development path at one level per season seems prudent. Assad, despite being the youngest is actually the most polished of the group, but at his age they are more likely to want to protect his arm late in the season and that is easier to do at a lower level. Uelmen has come on of late, however. If he is able to lock in more consistent control and command then he could work his way into the conversation during the second half.
Matt Swarmer will receive his call up at some point. Really, the only thing holding him back right now is the lack of an opening in the Tennessee starting rotation. Unfortunately for him, that rotation is already filled with five legitimate prospects, four of whom are getting their first taste of AA this season. Trevor Clifton is the one holdover from last season but 2017 was such a lost year for him that it is no guarantee that he receives a promotion any time soon, despite showing improvements over the first two months so far. So, Swarmer will likely bide his time in Myrtle Beach and continue to work on his changeup and finding a way to more effectively retire left handed hitters.
The other five members of the Myrtle Beach six-man rotation are new to High-A and will likely remain at the level throughout the year. It is possible that one of Alex Lange, Keegan Thompson or Tyson Miller receive a cup of coffee in AA at the end of the season but I would not expect any to see extended action there. Big lefty Bryan Hudson is almost assured to remain on a one level per season trajectory.
There could be some movement among the relievers. Jordan Minch is currently in his third season in Myrtle Beach. His time there has proven wildly inconsistent, thus why he has spent so much time at the level, but an early season mechanical tweak has shown exciting early returns. Minch has been absolutely dominate over the past several weeks and I would expect the Cubs to challenge him with a promotion to Tennessee in the near future. The Smokies have been without a left handed reliever all season so his addition would be a welcome one. Bailey Clark has already received one promotion this season, but I would not rule out a second later this season if he continues to throw strikes and maintain his current stuff. Another option would be Tyler Peyton. He has quietly taken over the closer role for the Pelicans from a struggling Jhon Romero and has enough stuff and control to warrant consideration if he keeps up his current level of performance.
I touched on the situation in the Smokies rotation above. None of the five pitchers figure to see any time in Iowa until the 2nd half at the earliest. Trevor Clifton is still trying to right the ship after his 2017 campaign ended in disaster. He could receive consideration in the 2nd half, but I lean toward handling him like they did with Duane Underwood last season. Let him re-establish himself without added distraction. Similarly, the main objective for Oscar De La Cruz is simply to make it through a full season healthy.
The other three members of the staff will receive consideration for promotion in the 2nd half, but health and the number of openings on the Iowa roster will play a determining factor if all three make it there before the season ends. Thomas Hatch will receive priority. He already received a non-roster invite to spring training this year and I expect the Cubs would like to give him an extended look in AAA during the second half as they prep him for next season when he will surely be one of the five starters at Iowa and will need to be ready for potential spot starts in the Majors.
Michael Rucker and Duncan Robinson could get looks in AAA this year as well, but unless there are injuries, their opportunities may come as relievers. They will be forced to compete with Dakota Mekkes, Craig Brooks and a couple of other right handed relievers. Iowa simply will not have enough room to accommodate everyone. Just like with Hatch in the rotation, Mekkes and Brooks will get the first chances that do crop up.
This situation obviously depends entirely on the health of the pitchers in Chicago. When everyone is healthy, none of the pitchers that began the year in Iowa figure to be able to force their way on to the Cubs 25-man roster. Once rosters expand in September the team will undoubtedly give Adbert Alzolay his first taste of Major League action if it hasn't already occurred by that point. Relievers Justin Hancock, Randy Rosario, Rob Zastryzny, Dillon Maples, Cory Mazzoni and Shae Simmons will all get consideration, as will starters Luke Farrell, Alec Mills, Duane Underwood and Jen-Ho Tseng.
The team will obviously not recall everyone but at least five of them will get a shot once the Iowa season ends in early September. If I had to guess right now: Alzolay, Hancock, Rosario, Zastryzny, Maples and one of Mills/Farrell/Underwood will be summoned. The team will also have Drew Smyly available assuming his rehab progresses as expected. That would give the team three lefties (including Smyly) and three righties to fortify the bullpen and another available starter (Alzolay) should they wish to go to a six-man rotation at any point or just rest someone as they prepare for the playoffs.