All three players are among the more experienced players in Ruben Amorim’s squad and have been regulars under the Portuguese tactician at the start of the season.
Maguire has featured in all but one of Man United’s eight games across all competitions, though only three have come as a starter.
In an interview with The Times, the Man United legend said: "Shaw, Maguire, Casemiro, they’ve all been great players but they’re at a stage of their career now where you get found out in the Premier League if you’re not physically good enough.
"Their bodies are not athletic enough, they’re not strong enough, they’re not quick enough. They’ve dropped to a level where they can’t cope with what’s needed in the Premier League.
"Every player in the Premier League is an absolute machine. They’ve got five per cent body fat, they can run, they’re strong, they can head it.
“Manchester United are carrying two or three players that are just not capable of living with it."
Harry Maguire is reportedly in line for a new Manchester United contract
“We got sucked into that one, and there’s been quite a few like that," Scholes added.