Manager Jim Tracy said Brothers, 24, has some issues regarding the tempo of his delivery that are affecting his command, particularly of his fastball.
"He's out of sync," Tracy said. "Everything's too fast right now. His body's too fast. His mind's working too fast. He's in a hurry to get things done. He's seeing the result before working the process, and so we need to slow that down and that needs to be done in Triple-A for a period of time so we can get him back.
"I don't think it's a real hard fix, because I don't think he's out of whack that badly mechanically to where this couldn't be a short stay and a fairly quick fix, but we'll see."
Brothers was a supplemental pick after the first round in the 2009 Draft and reached the Majors in June 2011, spending the balance of the season in the Rockies bullpen.
Brothers, a power arm with a fastball at 95-96 mph and a slider at 88-89 mph, began this season in a setup role with right-hander Matt Belisle as the bridge to closer Rafael Betancourt. Because of the high expectations the Rockies have for Brothers, Tracy said, "Having this young man pitch in the fifth or sixth inning of a one-sided game is asinine in my opinion, because of ... what it is you want him to do moving down the road and the importance of the innings that you want him to pitch."
Tuesday at San Francisco, Tracy said he thought Brothers had gotten "over the hurdle." In that game, he walked the bases loaded with one out but struck out Brandon Belt and Melky Cabrera to keep the game tied at 4. The Rockies won 5-4 when Marco Scutaro homered in the ninth.
Tracy said the seven pitches Brothers threw to Belt and Cabrera were "the best pitches I've seen thrown this year" by a starter or reliever, Rockies or opposing pitcher. But in the eighth inning Thursday against the D-backs, Tracy said Brothers "reverted back" to his faults while allowing two hits, two walks and four runs in two-thirds of an inning.
When Tracy spoke with Brothers about his demotion, he asked the reliever when he was having difficult innings whether he was simply trying to escape unscored upon, thinking that would help keep him in the big leagues. Tracy said Brothers admitted that was the case.
"'That's not the state of mind I want you in.'" Tracy said. "'That's the wrong state of mind to have, because when you have an arm like this and stuff like you have ... you're just trying to survive. And you know something, in order for us to be the kind of team we want to be moving forward, you can't just be here surviving. You need to be here dominating.'"