I think one reason might be that he's fed up with them.
It might only have been for these last two games but he clearly wanted the wide players to be ones that will work really hard, be more attentive to their defensive duties and not shirk physical battles as much.
I wouldn't be surprised if he just goes with this plan to try and grind out points / wins until we either pick up form and need a bit more guile and it's easier to accommodate one of them; or we sign someone who does the hard work and can produce the skilful stuff fairly regularly.
Wouldn't be surprised at this at all and I think if it were me I would probably do the same until we were comfortable.
Why keep playing mirallas and deulofeu if they can't provide what we need?
Martinez used to play players based on the fact that they were good, even if they didn't work in that system and we got beat time and time again.
Play the system not the personnel, I'm fine with it.