For example, Tommy Morrison winning a UD against George Foreman. A fighter with a poor chin beating a fighter with massive power. Wladmir has a good number of wins against guys who could really bang. Ray Austin, Lamon Brewster, Hasim Rahman, Samuel Peter, DaVarryl Williamson, Jameel McCline, Derrick Jefferson, Phil Jackson... Lennox Lewis fought maybe the best collection of punchers ever, and therefore I feel he has a good solid chin. Wladimir, in my opinion, has a touchy chin... Not terrible, but I find it pretty remarkable he's fought that many punchers and only had his ass on the deck a few times in the non-losing efforts. Down against Williamson, Samuel Peter... Still, impressive. What other examples are there?
Morrison vs Foreman was the first that sprang to mind. Norris vs Mugabi? Not that he had to evade much.
Another good one... Oleg Maskaev had a shitty chin, but won several fights against huge punchers. Alex Stewart, Courage Tshabalala (Broke Maskaev's ribs, good thing he didn't connect on that chin), Derrick Jefferson, Hasim Rahman 2x.
Austin is not a top drawer puncher,neither are Jefferson,McCline,or Jackson,take a look at who they stopped,and who they couldn't. Williamson can hit but not phenomenonally. Brewster is too slow of hand and foot to connect with his big left hook ,with any regularity. Rahman was well past it.Peter is a crude clubber,who lacks technique and stamina,his swings usually end up around the back of your head. Morrison ran all night against Foreman ,if he had traded he would have been iced. Ali fought the best collection of punchers ,and they were for the most part in their prime. Walcott fought a goodly share of them too. Lewis's chin is underated,but not top drawer,imo.
There is little evidence that Wlad has a 'touchy ' chin. I rarely see Ruiz tagged with that label. He was cleanly Ko'd by a big puncher. Wlad took a bigger shot (actually several) from an even bigger puncher and got back up. To your question, While not completely chinny, Spinks won on one card against a formidable puncher in Taylor. Kahn survived and defeated the hard-hitting Barerra. Douglas did OK against IroN Mike.
Corrie Sanders an 'even bigger puncher' than Tua? I don't reckon so. Ruiz wasn't stopped by a Brewster or Purrity either.
Sanders IS a bigger puncher than Tua (one of the few). And Wlad's losses to both Brewster and Purrity had little to do with chin and much to do with exhaustion (conspiracy theories aside).
Cuch, Wlad was ko'd in all of his losses, and was knocked down by Peter and Williamson. He IS chinny. Ruiz can take shots. He can be hurt, but he's not chinny at all.