If you can find multiple ruck contests where Sandi jumps at the ball, and hits it near the apex of his jump, I'll eat my words. 90% of the time, he's hitting the ball while standing on the ground, having landed after hitting the other bloke. The physics are inarguable: if you are taller than the other bloke, and you are both on the ground by the time the ball arrives, you'll win the contest. It's savvy. But it's not going to lead to a positive free kick count every time. That's ok. He wins 43 ruck knocks a game, and over his career has won more free kicks than he gave away. It's a great result. Given how many ruck knocks players contests, the difference between the ruckmen is basically negligible.
Career
Sandi: 1.2 For, 0.9 Against
Alleged Serial Cheat: 1.5 For, 1.1 Against.
As for his marking, he is going to injure people the way he flies at the ball, but he's just as likely to injure himself. As with everything, he relies on athleticism, with little idea about how to actually approach the situation like a footballer.
And why we're at it, can we please agree that 'going back and looking for evidence of something we are convinced is happening' isn't actually objective evidence. In 100 ruck contests a game, I'm sure you'll find whatever evidence you want to demonstrate that one ruckman or the other is giving away free kicks. Rucking is a dark art, and more often than not umps get decisions wrong. Rucking decisions really hurt, especially in the centre square. Best to make as few call as possible, I reckon. .