Go forward isn't about 'worrying defences'. It's about running at a set defensive line and moving it backwards. If you want to 'worry defences' get out wide where there is some space, or hit some short inside passes where you might find an isolated defender. Both things that Paulo does.
Lets not look at the manly stats because Mannah looked like a good prop against those pretenders. lets see how Mannah goes against Dogs.
That Penrith trial showed Mannah to be the worst forward on ground. He was constantly man handled which resulted in a slow play the ball