I'm not sure what ages Thome, Jones, and Canseco were when the Sox had them but I think putting Dunn in that group is pretty accurate. He gives solid power numbers but isn't necessarily a guy you'd want up in the clutch. He's had his moments and hot stretches but he isn't nor ever was the end-all-be-all.
I think his new approach at the start of the season of not taking walks was an awful idea from the get go...guys like him and Thome add value from getting on base in addition to the homeruns. To try out a different strategy wasn't very smart and the Sox should take just as much blame as he does for that.