Up to now? Perhaps marginally, given that the Cubs' pitching has been rock solid post-TDL.
However, the key would be in the playoffs and down the stretch. Having another SP would help juggle Horton's and Boyd's load management (although it would add a complicating factor in Cabrera's load management since he's never pitched more than 130 IP in a season) while also allowing Soroka to heal up. Additionally, a top three of Imanaga-Boyd-Cabrera, with Horton as a potential 4th starter/long man, would be downright lethal in the playoffs.
Cabrera's team control would also be the proverbial icing on the cake.