I think you are making this up...
Yearly averages were 30, 61, 62. Blayke is 43, 41,43. Averaging that out it is not "nearly twice" as much. You might want to check that your Epson calculator hasn't been hacked by the Russians.
Notwithstanding them having completely different coaches, playing styles, and rules, the difference here is maybe 1-2 times per game where he takes the tackle instead of finding a runner. Running metres is completely irrelevant.
Has that been measured? Does he get quick ptb when he scoots on his own, or only when he runs as a forward with support?
This is just completely incorrect. Across the period you are referencing Blayke makes more tackles per game. 51 vs 47. It's still irrelevant though, because making a few extra tackles per game could just be the result of being on a team who has the ball less.
Offloads! Now that's a stat which tells us who the best hookers are!
Irrelevant. Try assist is a fantasy stat. It doesn't tell us who is good.
Coach seems happy with him. I think he has been great. Needs to clean up the errors, but otherwise he is playing exactly how the team needs him to. Solid in defence, great service, play a link-man role when needed, talk to his halves, etc.
That must be why they moved him to lock.
... which was after he moved to lock and became their best player.