Zimmermann has thrown 108 2/3 innings over 17 starts, and at that pace he would make only eight more starts for the remainder of the season. If the Nationals are able to hang around the wild card race deep into the season, they will eventually lose the 25-year-old who, with a 2.82 ERA and a 3.62 strikeout-to-walk rate, has become their best pitcher. Zimmermann is on the innings limit because this is his first full season after Tommy John surgery.

“It’s not a great situation,” Manager Davey Johnson said. “But his welfare is more important than any particular game.”

Despite Zimmermann’s Sunday start, the Nationals will keep Ross Detwiler, called up to start last night, on the roster to swing between the bullpen and the rotation. The Nationals will still keep Detwiler on his usual between-start schedule while keeping him in the bullpen for insurance if they need a high number of relief innings.

“I want to keep him,” Johnson said. “I want use him as your typical left-handed reliever. He’s strictly long. He’ll get his throwing in between his pitching. He’s a valuable product, a young left-hander who throws the ball good. So I won’t overuse him.”