Former Ajax boss Ten Hag has come under increasing pressure as United bid to put their worst start to a season since 1962-63 behind them.
McTominay insisted all the hard work by the players and coaching staff behind the scenes will soon start to pay off.
The Scotland international told the club’s official website: “There’s more that goes into it when you’re not playing well and you’re not doing so well.
“I know the fans don’t want to hear that, they want to see results and performances and I think they want to see the players smiling and happy.
“It’s not quite happening at the moment, but I’m 100 per cent sure that the manager can put that into practice and it can come off. I’m sure of that.”
After successive 3-0 home defeats to Manchester City and Newcastle, United play at Fulham on Saturday and face Champions League group rivals Copenhagen in Denmark next Wednesday.
“We have to win, that’s always the thought process,” McTominay said. “Obviously my thoughts are with the fans at the minute because we’re not playing well and it’s difficult for them.
Obviously the fans will hear the generic response of ‘we’ve got to stick together’, but it’s true— Scott McTominay
“They pay their hard-earned money every week to come and watch us and the least we can do is play well and win football matches.
“It’s not quite happening at the moment, sometimes that’s football, but I feel like for us in that dressing room we have to stay tight and keep a clear head, and we can’t get too emotional with everything that surrounds us. We’ve got to block it all out.”
Ten Hag has urged his players to “stand up” and work “shoulder by shoulder” and McTominay agreed a united dressing room is key to halting their slide.
“Everyone knows that we’re not in our best period at the minute. We have to stick together, that’s the most important thing,” he said.
“Obviously the fans will hear the generic response of ‘we’ve got to stick together’, but it’s true.
“Everyone wants this football club to succeed and we have to pull together and try to be as good with each other as possible in the dressing room to get those results going our way.
“I feel like we’ve got more than enough talent in the changing room to do that and whenever you look at the boys who are playing, but obviously something isn’t quite clicking.
“That’s up to the manager and the players to fix that and I’m 100 per cent confident that we will.”