Early on in what has been a tumultuous reign at Camp Nou for Koeman, he told midfielder Puig he would not be counting on him this season and that he was free to leave on loan.
That conversation swiftly became public knowledge, which reportedly frustrated Koeman and led to a showdown.
El Pais reported on Sunday that the Dutchman was annoyed about how quickly details about his decision on Puig made it into the media.
Puig, 21, was labelled "a leaker" and had his attitude questioned in front of his team-mates before he was sent to the stands for the Joan Gamper Trophy match against Elche.
The dressing room reaction was said to be divided.
Some senior players have general concerns about the attitude of the club’s younger players and backed Koeman, who had just replaced Quique Setien.
But others felt there had been double standards because Koeman’s phone call with veteran striker Luis Suarez about finding a new team had also been widely reported.
Suarez went on to join Atletico Madrid soon after.
Despite Barca’s struggles this season, Puig is yet to start a match in 2020/21.
He has come on as a substitute once in La Liga and three times in the Champions League.
Puig had a big reputation at La Masia and burst on to the scene at the Camp Nou last season, particularly impressing after La Liga recommenced after lockdown.
After taking over, Koeman told the club hierarchy he planned to favour a two-man midfield of Frenkie de Jong and Miralem Pjanic, as well as asking them to pursue the signing of Gini Wijnaldum from Liverpool.