However, the story had already made the headlines the evening before in Germany, and Eintracht sporting director Fredi Bobic accused Bayern of leaking the news, a move he called "annoying, unprofessional and lacking respect".
"We were very professional".
"It's hard to get to this stage of the competition and that's eight years in a row we've done it", he said.
"Secondly, we thought for a long time about when we should tell the Frankfurters".
Heynckes took over following ex-Chelsea boss Carlo Ancelotti's dismissal in September and led Bayern to their sixth Bundesliga title in a row.
Sandro Wagner stood in for the rested Robert Lewandowski and took his chance with a first-half brace, winning praise from Heynckes.
Nico Kovac. Pic TF-Images Getty Images
"All the boys are in top form right now and that just emphasises the great atmosphere in the squad".
"We're very happy that we could win Niko Kovac as a new coach for Bayern", sports director Hasan Salihamidzic said.
Without doubt the biggest losers of the managerial appointment, Eintracht Frankfurt have lost a promising manager that had transformed the club in a two-year spell. "He does it excellently, so for sure he is predestined to become coach of Bayern Munich".
After the end of his playing career Kovac was briefly an assistant coach in Austria.
"We were obviously surprised especially in this phase (of the season) we are in which is extremely important for us", Bobic said.
The Croat, who had also coached his country at the last World Cup in Brazil, had impressed by helping Frankfurt survive relegation in 2016 before leading them to contention for a European slot for next season. Bayern's loss is Hoffenheim's gain, however, as the young coach can continue to build his team to climb the Bundesliga table.
Bayern was initially in talks with former Borussia Dortmund coach Thomas Tuchel, but he informed the club that he had agreed to take over another team while it was still trying to convince Heynckes to stay.
BoSox off to best start in 118-year history
The right-handed Cobb started 29 games previous year and finished the season 12-10 overall with a 3.66 ERA and a 1.22 WHIP. Red Sox 7, Orioles 3. "Right now we are doing everything right and having fun".