I'm saying that yeah Sissoko is better at carrying the ball up the pitch than Auier, I'd also say that he's better at doing that than Davies and Tripps too, in fact, this season that's been one of his features he brought to the team. It's valuable to us. Let's face it there wasn't any defending that was required by us, we had the ball and the territory, Watford were for the most part comfortable (bar a few Son moments) until Lucas came on and the dynamic of the game changed.If it was for tactical reasons ONLY, to allow Moura to come on and run at their defence, why not sub Sissoko off ?
Subbing Sissoko would not have altered any change to the new approach and we would of have a "specialist" RB/WB on the pitch.
Unless as you say, Sissoko is better at running from deep and carrying the ball, which in effect is what a WB should be doing anyway.