Having lifted the mood at the club somewhat with victory at home to Chelsea, United took a major step backwards over the weekend at Old Trafford as they fell to a dismal 3-0 defeat to Bournemouth, with the Cherries winning at the ground for the first time in their history.
Ten Hag's side were hugely impressive on home soil last season, unbeaten in 31 matches at Old Trafford before they were beaten by Brighton in September. Since then, Crystal Palace, Galatasaray, Manchester City, Newcastle and now Bournemouth have all come away with wins.
It leaves United sixth in the Premier League table, six points off the top four, and they will exit the Champions League on Tuesday night unless they beat Bayern Munich and Galatasaray also draw with Copenhagen.
Speaking ahead of that final group-stage match in Europe, Ten Hag was asked about his side's struggle for consistency and he pointed to the injury problems at the back, with Lisandro Martinez, Luke Shaw and Raphael Varane among those to have spells on the sidelines this season.
"We had a regular team, not so many changes," Ten Hag said as he reflected on last season.
"Especially in our back line. That helps you. You get the routines in. We have to wait for that. I think it is personnel.
"We are not the only team - I see inconsistency from other teams in the Premier League."
United face an uphill battle to reach the Champions League last-16, and will not even drop into the Europa League if they are beaten by Bayern at Old Trafford.
"I never think in negative scenarios, we think positively," Ten Hag said.
"We have to win to stay in Europe; it is all about that. We have shown in the last weeks that when we are at our best, we can do it."
There have been reports in recent weeks of dressing room discontent at United, with claims that the players have grown frustrated with Ten Hag's training methods and tactics. The club responded by banning four media outlets from a press conference ahead of the win over Chelsea.
Scott McTominay has admitted that the atmosphere at the club has turned "toxic" under recent managers, but was adamant that was not the case under Ten Hag.
"The players feel that responsibility [to support the manager]," McTominay said.
"I feel we have big characters in the dressing room. Maybe with some of the other managers in the past [the atmosphere in the dressing room] has been toxic at times, but that is not the case now.
"The boys are fully behind the manager, that's the be all and end all."