OAKLAND -- The Jim Johnson era in Oakland came to an ignominious end this morning as the struggling reliever was designated for assignment by the As. The move came on the heels of Johnson allowing four runs (three earned) while facing four batters in the As 9-7 win over the Astros on Wednesday night, raising his season ERA to 6.92. Former A’s closer Jim Johnson has an ERA of 6.55 after Thursday’s outing.