In the past he's favoured a 3-4-3 formation...hard to see how we can do that currently with only 3 senior CBs, one of whom is injured. He's also played wingers (Solly March as an example) in the wing back roles.
Typically when a 3-4-3 gets announced on a match day the manager is immediately described as being too negative, too cautious etc. I guess it depends on the composition of the 4.
He's given young players chances...hopefully that continues at West Ham.
Welcome Graham.