He's not tops in the league by any measure, but that doesn't mean "he's not very good." For his career, he's at 4 YPC, would have likely gone over 1,000 yards rushing again this season had it not been for injury, and has hauled in 50, 58, and 41 receptions the last three years for 4, 4, and 2 TDs, respectively. Those are stats of a RB that you label "not very good." I could see "overrated" though with the way the media talks about him.