Grant Wahl, who wrote the book, said in an interview with The New York Times that the comments made by Donovan will get readers interested.
He also revealed how Beckham's 'people' initiated the move of the former Manchester United star becoming captain of the club.
"For me, it's all of a piece. The excerpt is out there and it's probably the most explosive stuff in the book and will draw headlines," Wahl told Jack Bell of The New York Times.
"But for me, the book is an arc. I've been following this team for almost two years, and seeing how people were responding and how they experienced it. I think Donovan was fascinating, slowly becoming disillusioned with Beckham, his people and their commitment to the Galaxy over time.
"In July 2007, right after Beckham arrived, Lalas and Yallop approached Donovan and told him that "people above me," meaning Leiweke, thought Beckham should become the captain immediately.
"A couple weeks later Donovan gave up the captaincy. In fact, it had been Terry Byrne who initiated the move the previous spring when he brought it up with Lalas and Yallop in Madrid. Donovan didn't learn it was Beckham's people who initiated the move until I told him in the spring of 2009.
"Here's the big American star who has given a lot to this team. I think Donovan would have given up the captaincy to Beckham without anyone approaching him. It would have happened organically. Donovan is not stupid."