Mackanin pointed to Morgan's 1-7 record and 6.62 ERA entering Friday night's 4-3 loss in 11 innings to the Cardinals at Citizens Bank Park. Morgan lost a Spring Training competition to be the team's fifth starter, but when he was promoted in April to replace Charlie Morton, who suffered a season-ending groin injury, he struggled. He recently rejoined the rotation to replace Zach Eflin, who had season-ending knee surgery Friday.
"He has to start doing something," Mackanin said. "One and seven with a six ERA is not good. I think he's better than that, but he has to start showing it.