Easy enough for one lock to push properly, but a good partnership goes beyond one lock pushing well. Why do you think Botha and Matfield were so much better when together?
Well, because they were awesome.
In the third Lions test, or scrum improved mightily when Kepu came on. Then Douglas went off for Simmons and suddenly the pressure came right back on. It isn't coincidence.
When you are talking eg backline pairing, with Horne and AAC (Adam Ashley-Cooper) or the Quade/Genia axis knowing each other a whole season (or more), then there are benefits. In the back row too this can be important.
But at scrum and lineout time the best practitioners come together, hammer out a balance at training, and make it work. Combinations are important, but only within the context of your role, so at scrum time:
Locks are the engine - they provide the majority of the power.
Props direct it and add their own push, playing the tricks at the same time.
And in the very near future, hookers will actually strike for the ball again instead of being a third prop.
Every tight five forward in this country should be getting the same basic instruction on binding, leg position, and power. There are no subtleties to the second row and nowhere to hide when your scrum is getting mullered. You're either bound tight and pushing, or you're not doing your job.
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I hate autocorrect ...