For mine, it is our play the ball speed coming out of defense. You speed this up, dummy half plays the ball to a short ball runner, you're playing against a retreating defense (see Parra today).
This means the defensive line is constantly back tracking (and what frustrates me no end with Taufua, because he does the hard stuff metreage wise, but the slow play the balls allows a defensive line to set).
Also, I stated this before the game started. While it's great to have strength in the forwards (ours has plenty), you need a mountain of mobility, and that's something we lack (Dogs have a similar pack to ours, but Des got away with it, because they also became ball players - for a while).
Defensive structures and ruck control can counter strong forwards. You just can't coach against speed. Speed conquers all if you can control the ball.
Even Tommy has a very slow play the ball. Wintertsteins is slow. Myles is STILL getting up from being tackled today.
Manly constantly play against a set defense. Other teams create plays that allow to play against a retreating defense. Toovey used to focus on "metres after impact". A lot of our boys go into the fetal position (Nate Myles) after being tackled. Again - allows the opposition defense to become set.
But you know what controls all of that? Fitness. You have to be damned fit, and be full of energy to pop up, create a very fast play the ball to a dummy half, who passes to an up-tempo, mobile forward continuing the roll.