To be honest, i don't think so, he was a great fighter but was into the best era in the history of the 154-160-168 divisions.
Graham never won a title because he fought in an era that had Terry Norris, Nigel Benn, Sumbu Kalambay, James Toney, Gerald McClellan, Roy Jones, Michael Nunn, Julian Jackson, Iran Barkley, Chris Eubank, Bernard Hopkins, Reggie Johnson and Michael Watson active at the weights he was fighting.
Ive not seen much of him, but judging by his record.. he has 6 losses, had 3 chances at a world title and lost them all, even lost a british title fight. he obviously had flaws/ something missing. You can't possibly say he's better than a fighter such as Carl Frampton.
If he couldn't beat Frank Grant for the british title, and couldn't beat Charles Brewer for the world title.. then he musn't have been as good as your claiming.