No, switching from Toni Nadal to Moya as a coach wasn't difficult. It was a smooth transition. After Moya joined the Rafa Team, Toni continued to travel with the team for a year. Besides, Moya was Rafa's childhood hero and they have known each other since Rafa was 12- 13 years old. Moya mentored Rafa on the ATP Tour, when the latter became a professional player at age 15, and they have been good friends ever since. Moya said he didn't need any period of adaptation to the Rafa Team because it’s like a family, he has always been one of the family members, even if he has been outside. Rafa and C.Moya were both born in Mallorca and speak the same language - Mallorquín (the variety of Catalan spoken in Mallorca). So, they can easily understand each other.
As for hiring Moya, Toni Nadal called him and offered him a job at the Rafa Team (and at Rafa's academy; Moya is the Technical Director of the academy.) Moya agreed on the condition that Rafa wants to win GS tournaments again.
An excerpt from Moya's interview with El Espanol in January 2017 (Translated from Spanish via Google):
¤¤ Question: "How did the opportunity to coach Nadal appear?"
C. MOYA: "Toni Nadal called me when I was playing the IPTL. He knew that I was no longer with Raonic and asked if I wanted to be part of the Rafa team and also academy. My answer was "yes" in principle, but I said I needed to talk to Rafa.
I needed to know if he was willing to do everything to win again Grand Slam tournaments, to become the world's number one again ... And yes, he did have a hunger to win. For me, that was fundamental."¤¤
El ex número uno habla con EL ESPAÑOL en Melbourne sobre su nueva etapa como entrenador del campeón de 14 grandes.
www.elespanol.com
Rafa said in September 2017 that Moya brought positive energy to the team.
Reuters, Sept. 2017: ¤¤ World number one Rafa Nadal says the addition of compatriot Carlos Moya to his coaching team has added freshness and positive energy to the Spaniard’s training routine.
Moya, a former world number one, joined Nadal's team to work with his uncle Toni Nadal last December and has helped revitalise the 31-year-old's career.
"Carlos has been a great support. He came with excitement and also the belief that with a few things, I could improve my results. And it has helped," Nadal told Spanish newspaper El Espanol.
"
It has been a breath of fresh air, positive energy. We have changed the way we practice and for Toni it has been also good." ¤¤
World number one Rafa Nadal says the addition of compatriot Carlos Moya to his coaching team has added freshness and positive energy to the Spaniard's training routine.
www.reuters.com