I’ve been employed as a specialist scrum coach for the past 3 years and agree wit what’s already been said. Especially Tom’s stuff about heavy in the gym and leave it to the technical side.
It annoys me though when coaches create scrum specific core work for players in field sessions. I can only assume this is a time issue and ensures the players are getting some ‘core’ work in, for those who don’t go to they gym themselves. Personally, I really like the levels of core strength training as discussed by Jim Smith in Combat Core. Essentially, build a base before SPP and execution in sport.
Funny you mentioned the “pushing out”/hoop tension issue, its something I’m hoping to play around with with one of the squads I coach. I think it could work well for engagement and the initial shove, but not sure after that ie resetting with weight coming through.