Reason for the move?
"For impact, level of influence and being able to teach and that's what I enjoy doing," Foster said. "I think I'm going to have a larger circle of influence."
"It's a great move for the organization," manager Ned Yost said. "We've had great pace of development for our position players [but] the pace of development for our pitchers has slowed a bit. Foster's a guy we think can get the program going in the right direction again. He knows exactly what we need at this level and how to develop it."
Moore said that Foster, brought in to aid the pitching coach, "made an incredible difference building continuity within our Major League bullpen." It's been a young but largely effective bullpen.
"Exciting, fun, never a dull moment, Romper Room, a lot of personality," Foster said.
Foster will work out of his home in Frisco, Texas, and will be able to spend more time with his family, which includes two teenagers.
His ultimate goal is to be a Major League pitching coach.
"I think that's a good step, handling all the pitchers in the Minor Leagues and the coaches," Foster said.
Bill Fischer, the Royals' senior pitching advisor, will take over the bullpen duties on Saturday, Sunday and Monday. For the rest of the season, the job will be split between Northwest Arkansas pitching coach Larry Carter and Omaha pitching coach Doug Henry.
Foster replaces Rick Knapp, who was named Minor League pitching coordinator in September 2011.