I think one reason Dunn's name gets brought up so much is that he isn't like other players and that makes people uncomfortable.
We keep wanting to compare him to other players and it keeps coming around that he just doesn't compare all that well. Adam is just... Adam.
From Base Prospectus a week or so back...
"Perhaps most interesting for statheads--if frightening for Cincinnati faithful--is Dunn's low, low similarity index of 18. According to the BP Glossary, "a player with a score of 20 or lower is historically unusual," which, of course, most of us already figured out when the 6'6", 240-lb Dunn stole 19 bases in 2002. In another couple of weeks, Dunn will eclipse the 100-homer mark. At the age of 24."
"Similarity Index is a composite of the similarity scores of all of a player's comparables. Similarity index is an gauge of the player's historical uniqueness; a player with a score of 50 or higher has a very common typology, while a player with a score of 20 or lower is historically unusual"