What a crock of shit to be fair. He's not in the team for his "end product" he's there for his workrate, and providing "key passes", which he regularly does, not assists or goals, but key to the goals we score, and as an attacking player he does far more defensively than any of our other attacking players, far more.
As an example, watch the everton equaliser at the weekend.
Their player gets the ball near the halfway line, Mahrez is about 2 yards away, he runs forward with it, when he gets near our box, Mahrez is still about 2 yards away, having "tracked" the run, at any point in that "tracking" he could have caught the lad (who even slipped at one point), and made a foul, preventing the shot.
Bernardo would never have let him get that far, he regularly puts a shift in, that the likes of Mahrez, and Grealish (and even Foden) don't even try too.