Boateng was left out of the matchday squad for the September defeat by Ancelotti, with centre-back Mats Hummels joining Kingsley Coman and experienced wingers Arjen Robben and Franck Ribery on the bench.
The Germany international defender revealed a contingent of players were left stunned by the coach, who has since been replaced by Jupp Heynckes, informing them they would not play in the hours leading up to kick-off.
"We sat in the meeting room and five of us were told an hour and a half before the game that we would not play, suddenly and without any explanation," Boateng told Suddeutsche Zeitung.
"The players in question were shocked, you can say that."
Boateng made just 13 Bundesliga appearances last term, with a shoulder injury sustained in December 2016 ruling him out for three months.
The 29-year-old found his rehabilitation difficult and struggled to feel comfortable in himself on the pitch once again.
"That was a dark time, especially since I had almost no injuries for a number of years, and then suddenly everything went full throttle," he revealed.
"I was able to play again after three months, but that was not the same Boateng.
"I felt like I had a different body."