Martinez has played CDM before at Ajax.
Can work extremely well in a diamond or take someone one of Mount or Bruno off to play a 4231 or 433.
I have wanted to see Martinez as CDM aswell.
He can play as the shadow/hybrid CB-CDM.
I'd love to see something like this
Dalot- Kambwala - Branthwaite-New LB
Martinez
Mainoo - Bruno
Sancho/Mount
Amad/Gwood - Garnacho&Rashford
Play a False CB & a False 9 in a false midfield diamond with Inverted forwards like Garnacho, Rashford, Gwood, Antony & Amad trying to utilise the False 9's passes.
We turn in to a back 3 if Martinez goes deep and let the attacking fullbacks go up the pitch.
Hojlund as our plan B.