I wouldn't read too much into last night's outing. Street came in the 8th -- so he's apparently not yet taken over the closers job -- and gave up an ER. Embree came in the 9th and he too gave up an ER. Not the greatest night for the A's bullpen all around. Street will surely get back his job, the only question is when, but it appears the team is not (yet) ready to make the switch, esp when Street has had some struggles getting back to form and Embree has generally been very effective in his fill-in closer role.
I am the Master. Don't question the Master. Just do what he says and be proud.