Mourinho replaced the Dutchman back in 2016 and oversaw a steady if unspectacular improvement that yielded a League Cup and Europa League double the following season.
However, the 'Red Devils' were unable to claim silverware of any kind last season as their greatest achievement being a second-place finish in the Premier League behind bitter rivals Manchester City.
A frustrating start to the new campaign that sees United trail Premier League pace-setters Liverpool by 16 points and the Champions League places by eight has seen Mourinho come in for significant criticism, but Ince insists that Mourinho should not be held solely accountable.
"It's tough on Mourinho because he came in off the back of David Moyes and Van Gaal," Ince explained.
"Under Van Gaal they went back big time, they went back two years.
"While Man Utd were going back, Manchester City, Tottenham, Liverpool, they were going forwards.
"He [Mourinho] had to try to get them up just to compete with those teams and it's been a tough time for him."
Such is the level of United's struggles that Ince believes they may even face a battle to secure a top-four finish between now and the end of the season, something their fans had assumed would be a minimum requirement ahead of the season getting underway.
"Are we talking about a case where Man Utd might be struggling year after year to make the top four?" he asked.
"Only one team are going to win the league. Man Utd are not going to win the league.
"They've got to try to win a cup and they've got to try to finish in the top four, which is going to be a tough ask for them."