In terms of posession and defensive style yes, but Maguire and Varane are by a mile our two best aerial defenders, and set pieces absolutely will be a struggle for us with a pairing of Lindelof and Martinez. We already struggle defending them as it is. Maguire in good form is a better option for our overall team than Lindelof in good form. Whether he can get back there is up for debate, but people are comparing his form in a disastrous squad last year and the early days of this season (where Martinez looked equally poor) are not really being fair in their assessment. If he comes in and has a run of games while still making the same errors, then fair enough, but he deserves a chance to redeem himself when he has obviously shown to have quality at other times of his United and England career.
We might struggle a little aerially, but I think we need to cope with that. Already before Maguire and Martinez had their first game together, I feared the pair of them would be a bad pairing and the matches they’ve played together haven’t really changed my mind (7 goals conceded in 180 minutes). Maguire compensates for Martinez in the air, but that is the only good thing. They are both defenders who attack the ball and opponent in front of them leaving an opening behind them. As ground duels tend to be a 50/50 chance or risk of being overplayed, they both need their partner to be a covering CB who care more about the space behind than the opponent in front of them. Both Varane and Lindelof are that. With Maguire and Martinez there will be the constant risk of them being overplayed without the cover behind.
On top of that I think Maguire is a bit too slow on the ball but that might be improved by instructions, as I don’t think he lacks that ability, just that he sees himself as a ball carrier.
Hopefully he's not out for long, but the club has to look for a long-term replacement. His injury record for us is really concerning. We already have multiple other areas that we need signings in, but this is another big issue.
He has started 8 PL matches this season and walked off injured in 2 of them. This must certainly give ETH something to think about. If he wants to continue to play Varane, he needs to rotate more to rest Varane, but also to keep the backups fit and ready and being able to form partnerships.