He's the exact same height and weight as Allen Christensen, and Christensen averaged 21 touches last year. Matty Stokes is smaller and lighter than Rioli and averaged 26 touches last year, his body size/type has nothing to do with it, unless you're talking about his sometimes-dodgy hammies. You don't need 30 touches to make an impact. Rioli can have a massive impact with 15 touches, but seriously, how often does he do this? Many of his games he won't even get to 15, and you can't keep defending a guy who will sometimes have 10/11 possessions by calling him an 'impact' player. It's a cop-out Hawthorn fans are forced into when defending him because the adoration he receives is completely inconsistent with his output.
That's one theory, and perhaps in some cases you're correct. However there is no doubt Rioli is overrated and I think most people genuinely believe this because he simply doesn't do enough yet he is still spruiked as one of the best players in the AFL. It's not just fans either, multiple football commentators have said it too. It's not a personal attack, you can be overrated and still be a good or even great player. It's all relative.
2013 - Christensen (92.7 still developing - future star IMO), Stokes (97.3, 1st season above 90), Rioli (88, first year below 90 since 09).
Rioli averaging 110 pre injury returns slowly and is genuinely inconsistent for pretty much the first time in his career - as with many players he struggled to truly overcome his hamstring injury.
Stokes last year (by far his career best, was immense from rd.19 and continuing it so far this year) equivalent of Rioli's previous four seasons.