defenders are stationary at contact...they are trained to get up off the line, set their feet and the upper body moves forward...they aren’t running full tilt in the opposition direction...if they did, they’d ‘lose their feet’ as it’s called by coaches in the NRL. I’d love to see a defender make a front on tackle, mid stride at full speed. I think you’ve picked up the wrong textbook. Also, unless the three defenders you speak of are Siamese triplets, I reckon they’d have a hard time using their combined 340kg as a simultaneous force...you can run between defenders you know? It happens. The third defender generally comes in after contact too...you should watch some footy.
I’m also not referencing one game from the weekend...he’s played plenty of games and I’ve been less than impressed with his work rate...I reckon Des might want more from him too...hence his benching on the weekend.