Faulting the manager is crazyy, yes he is also taking responsibility but do you want to blame him for the individual error caused by Casemiro during the game against Liverpool? Do you want to blame Erik Ten Hag for the players not converting the chances they had against Crystal Palace? What about the individual error caused by Harry Maguire during the draw against Brighton? How about the individual error again from Harry Maguire and Christen Eriksen against Twente? Y'all Manchester United are bloody inpatient punks who wants to see quick change that won't bloody last. I'm disappointed, and even if they want to sack EtH, y'all want to settle for mediocre managers. 
So who should be responsible for the current slump of the Manchester United team? Are the players thirsty to be responsible for the mistakes they made?I don't think so, the coach has full responsibility and the selection of players is also at the coach's discretion so whatever happens the coach must be responsible because it is his choice.
Ten Hag has been given the freedom in the last 3 seasons to build this squad as he wants and bring in players according to his wishes but he still failed to make Manchester United's performance better, meaning he failed and he deserves to be fired.
Regardless of Manchester United starting the process with their new coach, it may be better or worse, but at least Manchester United's management has made efforts to rise, not like now with Ten Hag.