He would join a game, play for 1 minute, and then quit. It's not once or twice, but for most games for a long time now.
This behavior ruins games. As a game starts, the team balancer would allocate good players to his team since he's a shit player who counts for nothing. When he quits shortly afterward, his place will be taken up by another player. Whoever that is will be vastly superior and stacked the teams badly. I've seen a number of times how he consistently ruins the team balance by quitting.
I don't mind noob players as long as they stick around and finish the game. Join and quit behavior is selfish and bad. It just ruins the games for everyone else.