Goellrich is coaching the Costa Mesa program through July 21, and then he'll take on his new assignment at Estancia, where he'll be a head coach for the first time.
He had also applied for the head coach job at Costa Mesa. Kiefer said interviews will begin next week.
Bauermeister offered the Eagles' job to Goellrich Thursday and he accepted.
"I took the job at Estancia because it's the best opportunity for me, currently, for both teaching and coaching," said Goellrich, 25, who has been a part-time physical education teacher at Costa Mesa the past two years. "I felt it was time for me to be a head coach."
Goellrich, who also worked as the pitching coach at Mesa, expressed excitement for his new job. But he also stressed he maintains respect for the players at Costa Mesa. He said he wants the Mustangs to succeed, on and off the field.
"He did a wonderful job coaching with our program," Kiefer said. "I would've loved to have him to continue. But the opportunity at Estancia is a good one. I understand why he wants to go there and I support him. He's a good friend of mine. It's just a situation that's better for him. We're going to do our best to find a coach that fits our program."
Bauermeister said Goellrich will continue to teach part time at Mesa, but that, "we're working to get him to Estancia."
Bauermeister, a former Mustangs baseball coach who graduated from Costa Mesa, described Goellrich as a great fit for the Eagles' program that had recent success under Matt Sorensen, who stepped down last month to take the job at Brea Olinda.
Coincidentally, Goellrich is an alumnus of Brea Olinda. He also played at Cal Lutheran. His first coaching experience came at Costa Mesa. Now, he'll be in charge of the Eagles.
Estancia won the Orange Coast League title in 2010 and this past season the Eagles won its first CIF Southern Section playoff game in 19 years.
Bauermeister said there will also be improvements to the facilities and the Eagles are expecting a scoreboard.
"We're excited to have him," Bauermeister said of Goellrich, who was on Costa Mesa's staff when the Mustangs won the Orange Coast League title two years ago. It was Costa Mesa's first league title since 1978.
Goellrich believes he can lead the Eagles to a league title as a head coach.
"I feel that this is a program that has a strong opportunity to win," Goellrich said. "I feel like we can win the league the next couple of years."