Tommy Birch | The Des Moines Register

AP

The Iowa Cubs have been a stopping point for some of the Chicago Cubs’ biggest contributors this season.

Ian Happ started the season in Des Moines. Kyle Schwarber tried to rediscover his swing with the Triple-A team. And guys like Tommy La Stella have come and gone.

More may be on the way when major-league rosters expand on Sept. 1. Here's a look at which players are in the conversation:

The leading candidates

Eddie Butler, right-handed pitcher

Butler helped the injury-riddled rotation in Chicago earlier this season. During a 13-game stint that included 11 starts in the big leagues, Butler went 4-3 with a 3.95 earned-run average. He’s put together a strong season in Iowa, where he’s gone 2-0 with a 2.17 ERA. With Chicago’s rotation dinged up and the bullpen still looking for help, Butler will likely be called back up as long as he comes back healthy from the disabled list.

Merle Laswell / For the Register

Jack Leathersich, left-handed pitcher

Leathersich struggled in his lone big-league stint this season but being a lefty and pitching out of the bullpen, he’ll likely get another shot. Leathersich has a power arm that can get strikeouts. He piled up 65 strikeouts through 41.1 innings with Iowa this season.

Rob Zastryzny, left-handed pitcher

Zastryzny has jumped up and down between the minors and majors this season. He’ll likely end the season in Chicago. Like Leathersich, he offers another left-handed arm. Zastryzny can pitch out of the bullpen or start. He missed substantial time this season on the disabled list and went 1-2 with a 6.57 in his first 12 games with Iowa this season.

Rachel Mummey/The Register

Victor Caratini, catcher

Caratini has had two different stints in Chicago and will likely have another. The Cubs need all the help they can get behind the plate with Willson Contreras on the disabled list and his return this season still up in the air. Caratini has torn apart opposing pitching in Triple-A, hitting .344 with 10 homers and 24 doubles in his first 76 games. He was making the most of his second promotion before being sent down.

In the conversation

Seth Frankoff, right-handed pitcher

Frankoff has been one of the most consistent pitchers in Iowa’s rotation. He’s logged 111.2 innings and compiled a 4.35 ERA in his first 23 games at Iowa this season. He’s in the midst of his eighth professional season and finally made his big-league debut earlier this year when he tossed two innings in relief. He can pitch in relief or start and has remained on the 40-man roster since his first promotion.

Dillon Maples, right-handed pitcher

Maples has been the success story of the season for the Cubs. The former prized prospect had never pitched beyond Class A advanced before this season but has worked all the way up to Triple-A this season. Maples added a dominant slider in the offseason to go along with a fastball that has been clocked in triple digits, and that’s been the difference for him. He’s not on the 40-man roster so the Cubs would have to make a move to make room for him.

Dylan Heuer/Iowa Cubs.

Worth noting

Pierce Johnson, right-handed pitcher

Johnson was once one of Chicago’s biggest pitching prospects. But injuries and inconsistent play forced the Cubs to send him to the bullpen. He’s had mixed results so far this season, going 3-2 with a 4.84 ERA through 39 games with Iowa. Johnson did get his first big-league call-up earlier this season and the Cubs may want to see more of him to figure out what exactly they have with him.

Matt Carasiti, right-handed pitcher

Carasiti began his career with the Colorado Rockies, but was shipped off to the Cubs this season for Zac Rosscup. The hard-throwing reliever struggled in 19 big-league games with the Rockies, but a change of scenery with the Cubs may help. He’s been off and on with Iowa and isn’t on the 40-man so he may be a long shot to get a call.

Jacob Hannemann, outfielder

Hannemann began the season in Double-A but was promoted despite struggling. The promotion gave him a fresh opportunity that he’s taken advantage of, hitting .259 in his first 69 games with Iowa. Hannemann is one of the few position-player prospects in Iowa. He was a third-round pick by the Cubs in 2013 and is 26 years old so the Cubs may want to give him a shot like they did at Triple-A and see if he sinks or swims. Hannemann could also provide some speed off the bench.