Strop, 27, is 0-2 with a 6.11 ERA in 22 appearances for the Orioles this season, allowing 12 earned runs in 17 2/3 innings. His control has been the biggest issue. He's walked 14 batters, including two in one-third of an inning Thursday night in Toronto.
Strop also served up a grand slam to Edwin Encarnacion, contributing to a 12-6 loss to the Blue Jays.
Strop has been charged with four runs and three hits, with three walks, in his last two appearances covering one inning, after surrendering only one earned run over 13 outings.
The Orioles can send Strop on an injury-rehab assignment before activating him from the disabled list. He's out of minor league options, but that doesn't preclude him from joining an affiliate on rehab.
Johnson replaces Strop in the bullpen. He flew into Toronto this morning and is working on limited sleep.