But four of those five wins have come against fighters decidedly smaller than Klitschko, who has weighed in 241 or 244 pounds in all of the fights. Compare that to DaVarryl Williamson (218), Eliseo Castillo (215), Byrd (213) and Calvin Brock (224).
This Saturday, at the SAP-Arena in Manheim, Germany, Klitschko faces 6-foot-6 American Ray Austin, who has weighed in anywhere from 238 to 255 pounds in his last five fights, in which he has compiled a 3-0-2 record. In his 31 career fights, Austin has drawn four times and lost three times. His losses came against Attila Levin, Harold Sconiers and Charles Hatcher. His draws? Lance Whitaker, Zuri Lawrence, Larry Donald, and Sultan Ibragimov in a totally unimpressive IBF title eliminator last July.
Austin's track record is not impressive, and only his management team could ignore that fact. No one is arguing that Austin is a truly proper opponent for Klitschko -- at least not on paper, with his track record. Austin's most impressive win is against Owen Beck, a split decision in 2005.
But what Austin believes -- and what I personally agree with -- is that his size will make for a difficult challenge for Klitschko, who has an inconsistent history against fighters that can match his frame and reach.
Klitschko can dominate most any heavyweight in the world when his jab is working. But can he keep Austin at bay like he did Byrd, setting up for the furious punches that send Byrd crashing to the canvas, and did the same to Brock, who was as close to a legitimate contender as you can get without doing something as ridiculous as putting champions against one another.
Wlad's resurgence truly started in his win over Samuel Peter, an unusually gutsy performance that saw Klitschko floored three times en route to a tight unanimous decision victory. But Klitschko has not been tested like that since, with Byrd never in the fight and Brock succumbing to Klitschko's jab and power after Wlad was bloodied and felt he had to turn up the heat.
Is Austin the guy that can give Klitschko another serious run? He sure thinks so.
"Styles make fights, that's why this will be a good fight. We match up at about the same height and reach. That's why this is going to be a good fight. I'm gonna make some rain fall on Klitschko come Saturday night."
If the Cleveland native were indeed to defeat Klitschko, it would be a seriously tough blow to Klitschko's career, perhaps even something he would have no real way of recovering from. This is seen by everyone as a total mismatch, and a fight that Wlad should win with ease. If Austin tests Klitschko, every single question that Wlad has ever faced will come right back to haunt him.
And Austin, at 36, is getting what will be his only shot at greatness if he loses. This is Austin's chance, and many would argue that he doesn't even deserve it. But it's here, and it's real. And Ray Austin will get his one and only shot at being a world heavyweight champion.
All he has to do is score the upset of the year.