A slightly rotated Red Devils side saw Maguire get a rare start this term, as Fulham took an early initiative in the game.
“We have a lot of competition for places and that's what a big club needs – strength in depth," Maguire told MUTV at full-time.
“I think you've seen today, after the first 20 minutes it was a really positive performance from the lads who stepped in, the lads who haven't played as much.
“I think the manager and his staff can rely upon us, they know they can make changes and we can do the job.
“It's good to be a part of the squad and if we're going to be successful this season, next season, and seasons after that, we're going to need a big squad."