Madison Keys says she switched coaches because she wanted a more full-time presence.
The 20-year-old was working with former No. 1 Lindsay Davenport, as well as Davenport's husband Jon Leach and Lisa Raymond.
But Davenport, a mother of four and commentator for the Tennis Channel, could only help Keys on a part-time basis.
"Obviously we still wanted to work together," said Keys, speaking to press at the Maria Sharapova and Friends event in Los Angeles. "But our tennis travel is insane. Like a mother of one wouldn't be able to do it... It just became a lot."
Describing it as a mutual decision, the world No. 18 added that she was looking for a more regular coaching commitment.
"This point in my career, I wanted someone who would be there every single day" Keys said. "She helped me so much, but we kind of went as far as we could."
The American is now being coached by Jesse Levine, saying they had a successful trial at the beginning of the off season.
"He hit with me before Charleston, and he did an amazing job," she said. "We've been working really well together."
In 2015, Keys reached the semifinals of the Australian Open, the quarterfinals of Wimbledon and the final of Charleston, but only reached one other quarterfinal during the year.
"I really want to have a consistent season," she said.