He doesn't?
It's surely hard to fit Marcelo into an attacking line-up of Ronaldo, Di Maria, Ozil, Higuain/Benzema/new signing, and so you'd think that this will make Marcelo more of a squad player which seems harsh given what many regard as a much improved season.
He plays where he wants.
Also, how many players does Mourinho have at his disposal in right and left back? Marcelo, Ramos and Arbeloa to pull the rest of the weight on both sides. No one else. Makes perfect sense to get another left back, since Arbeloa is more of a right back, and therefor can rotate much more.
How can we have Anderson when we have Scholes, Carrick and Fletcher playing in the middle? Oh and Gibson and Giggs? SAF rotates. Real aren't Barca. They don't stick with the same team every single game.
And like I said. It's well known that Mourinho wants a backup player for every position on the pitch who will not be a big weak link when stepping in. That's why he always has very strong benches. That's why he wins titles as well. Great people coming off the bench.
Look at his striking options. He uses one striker but would like to use two as well. He has Benzema and Higuain and Ronaldo can cover. Needs one more there and that's why he got Adebayor for loan.
In the middle he has Ronaldo, Özil, Di Maria, Alonso, Khedira, Diarra, Granero, Pedro Leon, Kaka, Canales and Gago.
Gago and Kaka haven't been around much this season so that leaves 9 players. Him bringing in Altintop and Sahin and the lack of playing time for Canales, Pedro Leon and Granero makes you wonder that he's not all to happy with all of them. So 13 players all in all, some of them will leave and Ronaldo covering two fronts.
In defense he had Pepe, Carvalho, Albio and Garay covering the CB with the before mentioned 3 players at full back. That's not great cover is it? Plus Casillas, Dudek and a young goalie that brings the tally to 25 (plus three of which he has acquired minus Adebayor).
27 players all in all with now more needed cover in defense and players yet to be sold.
I see nothing odd there. We've been using 23 players this season and that's not counting Bebe, Obertan Kuszczak or Hargreaves who are all part of the squad or mentioning Welbeck and Cleverley and Macheda and Diouf who were loaned out.
You say he's got many players when he's way more off our own count of players. I don't think he'll have a problem.