There's your space there...go for the space (trouble at the scrum).
The scrum is one of the least understood parts of the game, especially what occurs in the front row. Having played hooker and prop I consider myself a bit knowledgeable but there is still plenty that goes on where I'm left scratching my head. For example, why would any prop ever choose to lineup head to head? It's a form of the game chicken but here we're going to use our heads...brilliant. This sequence from Saturday's Chiefs vs Highlanders match stood out for its length and substance:
Plenty of issues with this sequence of scrums and Rohan Hoffmann has some very specific communication to clear things up (sorry for the long injury portion of the clip but it provides context). The first sequence is halted prior to the "bind" call due to the positioning of the Highlander loosehead. Hoffman is going through his pre-engage checklist and clearly wasn't pleased with the prop's positioning, "I've given you the mark...there's no excuse to go head to head...there's your space, go for the space." It's the second half but never too late to show control and a concern for player safety at the scrum.
Once he's satisfied the scrum comes together, ball goes in and is quickly won by the Chiefs but shortly after goes to ground. Take a look at the Chiefs tighthead for a clue as to where this scrum is going. The prop's bind is on the arm/shoulder of his opposite and it immediately comes down on the tricep which takes away his opponent's base/stability. It's intended to give the tighthead leverage and his opposite knows to drop the scrum rather than give ground this close to his ingoal. The commentators and every other rugby player want to see the ball out at this point but safety always trumps (8.3d) entertainment when a scrum has collapsed (20.4h). Hoffmann comes across the scrum, discusses something with his AR, and goes in to warn the props about angle (driving straight) and binding (on the back not the arm). What I find interesting is that he tells them he's relying on the AR's call if needed and goes back to the scrumhalf's side. I would have been inclined to stay on the far side despite the scrum being so close to the touchline as that was the side causing trouble.
The reset brings more of the same with the Chief's tighthead improperly binding and this time his flanker joins the front row by releasing his bind and joining alongside him to take on the Highlander's looshead. It's a sneaky move (20.1e) which can only be seen by the AR given Hoffman's positioning. The balls position and the movement of the scrum make it difficult to tell what effect this play has on the outcome but my guess is very little which is why they allow play to continue. A conversation should be had with both flankers to keep them bound and ultimately out of the front row.
The IRB's website provides a great overview of the trial scrum sequence. More to come on checklists and the scrum.