Frank's record is 24 fights 22 wins ,1 draw 1 loss. The draw was with Renaldo Snipes, the loss to Larry Holmes. Frank beat recognisable names like Zouski Stander,Lee,Casale, Jameson, New Jersey Champ , he is light years away from being the worst credentialed challenger.
There was never an "official" title on the line when Frazier had either of his fights with Holmes or Tyson. I suppose you could say that his fight with Holmes was for "lineage" but regardless had he won he would have left the ring with no belt. Therefore he's more or less eliminated from the discussion. Scott Frank had a padded record and if truth be told, wasn't very good. But being 21-0 with a hard fought draw against Snipes and wins over a few respectable journeyman removes him from the " worst" list.. Terry Daniels might be one of those guys who makes that cut, but I can think of a few who likely eclipse him.. Heavyweight championship history is full of men who had no business in the ring with the champ.
Douglas couldn't beat him. Buster broke his jaw but couldn't beat Tangstad. Tangstad had heart he deserves the respect.
Seldon beat Tony Tucker for the WBA title.(Before this fight only Tyson and Lewis could beat Tucker). Honorable mention Seldon was the first man who knocked out Tucker. Hipp dude wasn't so ****.The Morrison-Hipp was a good fight Hipp broke Morrison's jaw. hhonorable mention Mr. Hipp knocked out C. Woods in the first round at 0:27. Why do i say this ? Because Woods destroyed Puritty in the first round. Yes you read it well. This is the SAME Puritty who DESTROYED,HUMILIATED and CHASED the pathetic wladimir klitschko.