It’s been several days since the Cubs shuffled out a reliever and brought in another, so they were due.
This time, it’s Justin Grimm finally returning from an extended stay at AAA Iowa (Grote). With the Cubs, Grimm battled significant command troubles that not only tanked his strikeout rate (23.4% – which isn’t terrible, but is quite low for him) and bumped his walk rate (12.5%), but it also seemed to make him especially susceptible to hard contact in the air. His fly ball rate soared, and an insanely high proportion of those fly balls (37.5%) left the park.
Grimm’s last big league appearance was way back on May 7, before he was optioned to Iowa.
At Iowa, Grimm didn’t really get much better results, but that’s less the issue than whatever it was that the Cubs specifically wanted him to work on (we never got work whether it was a mechanical issue, for example). Grimm will likely be limited to middle relief/clean-up duty for now until he – hopefully – re-establishes himself. When Grimm is on, he’s fantastic.
As for Pena, he rides the shuttle back after giving the Cubs three innings of work in the Dodgers series. He’s got a 2.25 ERA in limited big league duty so far, but the peripherals haven’t been stellar. He’ll be back at some point.
This is the advantage of having a number of relievers at AAA with options left – they can be rotated like this to maximize freshness. Of course, the greater hope is that one or more of them break out and stick with the big team.