Jake McGee’s move to the DL twists Rockies’ trade deadline need; Nolan Arenado wows again in D.C.

WASHINGTON — The Rockies’ need for bullpen backing swelled Sunday when they put southpaw reliever Jake McGee on the disabled list because of a strained muscle in his back.

Colorado recalled left-hander Zac Rosscup from Triple-A Albuquerque. McGee has pitched as the Rockies’ primary setup man for closer Greg Holland. He is their second-best, late-innings reliever with a 3.27 ERA and a team-leading ratio of 3.92 strikeouts per walk issued.

General manager Jeff Bridich has said the Rockies are on the lookout for bullpen depth, with one or two new arms needed to shore up the back of the relief corps. As Adam Ottavino continues to struggle, and with Mike Dunn just now regaining form, a once-stout bullpen has faded to 12th in the 15-team National League with a 4.53 ERA.

Baseball’s trade deadline is Monday at 2 p.m. MDT. The Rockies acquired veteran reliever Pat Neshek from Philadelphia last week.

McGee was called on to prep for the eighth inning Saturday against the Nationals in relief of German Marquez, but he felt discomfort in his back and the Rockies sent him to the clubhouse. Manager Bud Black used Neshek instead in his Rockies debut.