Boston manager Alex Cora confirmed Johnson is the team's fifth starter, Michael Silverman of the Boston Herald reports.
As Johnson ramped up during a rehab stint, having him fill in for the injured Nathan Eovaldi (elbow) was widely presumed to be the Red Sox's plan,. Johnson was pulled after three innings and 70 pitches Sunday against the Orioles, and while Cora is sticking by him a starter, the manager expects improvement. "I think [Sunday] he was OK," Cora said. "Like I said, rehab starts, big-league starts are way different. He was OK. Hopefully for his next one he can do better." Meanwhile, Eovaldi has resumed throwing after a setback and is starting his rehab from scratch. Johnson could be the fill-in starter through the All-Star break.