Another in-house option is long-man Mike Montgomery. The Cubs traded for Montgomery at the deadline last season, sending slugging prospect Daniel Vogelbach to the Seattle Mariners in return for the left-hander. He has been an extremely valuable asset for the Cubs, both in the bullpen and as a starter.
He made five starts for the Cubs last season, and before being traded to Chicago he made 18 starts over the course of his career with the Mariners. So the experience is definitely there. But there are legitimate concerns with moving him into the rotation as well.
If he were to take over as a starter, even just in the interim, Brian Duensing would then be the Cubs’ sole lefty in the bullpen. Montgomery’s effectiveness in the bullpen has been crucial to the team’s success, and he sees a pretty significant drop in fastball velocity when he’s pitching as a starter. He could perform well as a starter, but if you remove him from the bullpen, that only creates an additional problem for the Cubs.
Remember, the Cubs still had left-hander Travis Wood in the bullpen when Montgomery was making starts. They shouldn’t expect to get that type of reliability out of Duensing.