They definitely didn't. I was there and watched him closely off the ball.
They weren't trying to cut the ball into him off by putting 2 men on him. What would be the point when 1 would do the job? I'm not exaggerating here, he literally doesn't move an inch when we're in possession and he doesn't have the ball. He barely even moves forward to support attacks going down the opposite side.
He literally just stands still, waits for the ball to come to him, slows the play down, draws 2 or 3 towards him, rips the arse out of them and puts a cross in. Which I'm not saying isn't effective or exciting to watch, I just don't see how it fits into Nuno's 'idea'.
I've never seen a professional footballer at any level play the way he did in that 45 minutes yesterday. It was totally unorthodox and it will take a hell of a lot of work to get him fully integrated into the system to the point where I'd trust him to be anything more than an impact sub in this side.
I'm not willing to write off Costa like some have and I'm certainly not willing to write off Nuno's system, which has gotten us so far, at the expense of one talented but completely mental footballer.