The Red Devils will have to settle for a Champions League qualification spot this term as they sit 12 points behind leaders Chelsea in fourth.
And, despite Louis van Gaal splashing in excess of £150million on new recruits last summer, McManaman believes the Dutchman will need spend the same again to be in with a chance this time next season.
I think they are £150m away from winning the title
Steve McManaman
“I think they are miles away, £150million away from winning the title," McManaman told BT Sport's Football Tonight show.
"I have been disappointed with the way they have played. I think the fact that they played so well against Liverpool and Tottenham has rescued them.
"I expected them to play much better and be closer, as in they have never ever been anywhere near challenging for the title this year.
"They have got a little bit closer at the end of the season as other teams have tailed off."