I think ego brought Roy back down to fight Tarver. He was in another stratosphere; he didn't NEED to fight Tarver considering the huge fights waiting for him at HW. But Tarver was running those big lips and Roy wanted to shut him up. A fight with Tyson would have made way more money and Roy could have picked at the fringe elite in the division and then called it quits with only 1 loss. At that point in his career Tyson would have been very dangerous, but very beatable.