Bruce, who was out of the Reds' lineup for Friday's 10-8 win over the Cubs, is hitless in his last 12 at-bats after going 0-for-4 with three strikeouts on Thursday.
"It's pretty apparent that I've not been helping the ballclub out too much lately," Bruce said after the game, "and he wants to give me a couple days to clear my head and get my work in [in the batting cage on Saturday] and be ready."
Over his last 10 games, Bruce is just 7-for-33 (.212) with 13 strikeouts, no home runs and four RBIs.
"He's struggling," Baker said prior to the game. "I haven't talked to him yet, but I mean, he hasn't looked much like Bruce the last week. I'll probably give him today and [Saturday] off, and hopefully get your head together."
Baker didn't sugarcoat his comments about Bruce, making it clear the Reds need his bat to come around while locked in such a tight race in the National League Central with the Pirates, who started Friday trailing Cincinnati by just 2 1/2 games.
"If you've been watching [our games], you've seen it, too," Baker said of Bruce. "He's just not swinging well. He's feeling for the ball. He's not attacking. It looks like he's messed up right now."
Baker hopes taking a step back from playing for a couple days lets Bruce see the game from a different perspective and allow his mind to clear a little.
"That's kind of a last resort," Baker said. "As much as we need him, he hasn't been hitting. It's not like we've been hitting with him, so I'll try somebody else and give him a couple days just to kind of clear the [mind]."
Bruce, who was replaced in right field by Xavier Paul on Friday, was available to pinch-hit.