A number of players said communication was an issue with Bosley.
"Thad was a good guy, he had a good heart. He just didn't fit with us," Rangers outfielder Josh Hamilton said. "He's professional in the way he approaches the game and the way he approaches teaching the game, but it just didn't mesh with our clubhouse. ... The communication was just lacking."
The Rangers hired Bosley in November 2010 after then-hitting coach Clint Hurdle took over as the Pittsburgh Pirates' manager. Hurdle followed Rudy Jaramillo, who served as the Rangers' hitting coach for
15 seasons before leaving after the 2009 season.
Bosley had hard acts to follow in his two respected predecessors.
"There's always a transition -- that's pretty natural," said Michael Young, the team's leading hitter at .311 entering Wednesday. "Having said that, it's probably pretty difficult on anybody to come in and try and replace those two guys. In my mind, those are the two best hitting coaches in the world."
Shortstop Elvis Andrus noted that Bosley had a different approach than Jaramillo and Hurdle.
"I think, for me, I need a hitting coach that can teach me and make me better mentally more than physically," Andrus said. "I wish [Bosley] the best, but he was more physical and technique. ... Rudy and Clint, they were more into the mental part of the game."
Texas will now have to adjust to its fourth hitting coach in less than three seasons, but Coolbaugh, a former Rangers third baseman, is a known quantity to the club. This is his fifth season as a hitting instructor in the organization. He spent the 2007-08 seasons with Double-A Frisco before joining Triple-A Oklahoma and then Round Rock this season.
"Coolbaugh has a relationship with those guys, they've been around Coolbaugh," Washington said. "Quite a few of them have been down at Triple-A where Coolbaugh had a chance to work with them. I think Coolbaugh's going to do a great job. He's sharp. We won't miss a beat."
Coolbaugh left Round Rock on Wednesday afternoon and joined the Rangers for their 7-3 win over the Tigers. Minor League hitting coordinator Mike Boulanger will take over as Round Rock's hitting coach.
Coolbaugh hopes to ease the apparent communication problems immediately.
"For me, I try to talk to them on a daily basis," Coolbaugh said. "I think open-ended communication -- these guys can come to me and ask me anything that they want ... and know that I'm going to have good information for them -- that's the key."