This line of thinking, exposes a fundamental flaw, in the understanding of the game. No, Ron Hainsey isn't a top pairing guy, most certainly not on his own. But, his play when partnered with Rielly, made the Leafs top pairing better, because he covered up for Rielly's defensive flaws, allowing Rielly to focus on the offensive side, that he was good at. Without a defensive conscious, Rielly's offensive, and defensive game suffered. If you want to maximize Rielly the player, you need a strong defensive partner for him, and frankly hopefully someone better than Hainsey.
This is why a guy like Hyman works on a top line. I don't think anyone would even call him a top six forward, on his own merits. But he does things on the ice, that allows the more talented players to excel, and he makes his line better.
These players are the glue, that makes the offensively talented players, do what they do best. Obtaining another top line RHD, that is offensively strong, but defensively weak, is the exact opposite of what Rielly needs to be at his best, or what the Leafs need to be competitive. It's why a guy like Tyson Barrie isn't a good fit for the Leafs, or for Morgan Rielly. Barrie will continue to put up points, and be a positive PP contributor, with whatever team he plays for next, like he was with Colorado, and Toronto. But to put such a player with Rielly... it doesn't work. The same reason that Risto wouldn't be the right fit. Rielly is our PP guy... Risto is a PP guy as well.... a good one at that, but Risto wouldn't get PP1 opportunities, and those skills would be wasted with us. Risto isn't strong defensively, and really the only positive he brings for the Leafs, that is a Leafs need, is that he's physical.
This isn't Playstation, or your Xbox, where you put the highest rated players together, and create an all-star team, this is about building teams that work, and finding pieces that fix your flaws. Leafs need a strong defense first guy, who can play RD, can skate, and hopefully is physical as well.