Colorado’s switch to a four-man rotation with starters on 75-pitch limits hasn’t exactly worked wonders, but the Rockies are sticking with that setup for the remainder of this season and plan to continue using it next year as well.
Troy Renck of the Denver Post reports that they’ll make a slight change, essentially pairing each starter with a “piggyback” reliever who’ll be expected to throw around 50 pitches. And in theory 75 pitches from the starter and 50 pitches from the reliever would get the Rockies deep enough into games to then rely on more traditional bullpen usage.
Coors Field and pitching at altitude has made it extremely tough for the Rockies to get consistently good or even decent starting pitching for basically their entire existence, so experimenting makes some sense and pairing pitchers is an interesting concept. Of course, it’s worth noting that the switch to a four-man rotation hasn’t really done much good so far.
Before the switch Rockies starters had a 6.28 ERA and since the switch Rockies starters have a 5.61 ERA. So they’ve been better but still really, really bad and the extra stress placed on relievers has caused the bullpen ERA to rise from 4.00 before the switch to 4.52 since. Basically all the improvement with the rotation has been canceled out by the bullpen getting worse (and throwing more innings).
Overall their team ERA was 5.38 before the switch and is 5.04 after the switch.