On McGregor I’m sure he could, if he had wanted to, could’ve forced a move to a Burnley, Fulham yo-yo club if he really wanted to. Or someone like Everton, a bottom 6/8 EPL club.
There are plenty of players worse than McGregor who have played EPL so for me he probably has had the opportunity to test himself against better players every week but just maybe not for a “top” EPL team.
I don’t mean this as a slight on McGregor or James McArthur but McGregor is at least at the same level if not better and McArthur played plenty of EPL games.
Just because Spurs, Newcastle or whoever the current 4th-8th clubs don’t want you doesn’t mean you aren’t good enough to play in that league.