On recent form you are absolutely correct, his defensive pressure is very poor. But I will caveat that with it depends on how he was asked to play. He is such a good ball player they may have encouraged him to be that early and worked the team/set up around that, or he wasn’t and they lost faith he could at all. Hard to know and is pure speculation.
Either way, a player that explosive and strong changed the way you play around the contest, Rioli has the explosive part but not the brute power, however when he plays in the middle he is very much a ball player rather than purely defensive.
I think if you put stringer in a defensive spot at the contest, say in the sweeper position at centre bounces he will naturally have more of a defensive mindset, he would turn any 50/50 on the defensive side in a positive clearance as he can get out of situation most can’t.
I guess the point I’m trying to make is allot depends on how you play him, and until 5 rounds in we are not going to know how much was a stringer issue and how much was a dogs coaching issue. IMHO It’s an exciting side issue to watch unfold next season.