So you have Quad and Henry with 2 dominating X factors. You can sort of counter those but you force your opp to run secure tackler, using up AP he wouldn;t have to use to stop other RBs. You have Milk Man, Tank, Maniac. There is no counter to Unstoppable force. Therefore, EA could release pass rushers with 99's at every attribute that would not be as effective as these cards. Sure the X factor turns off but they re-engage after a series or two .
If you are playing to win, would you really use anyone else except Quad/Henry/Milk Man/Tank/Maniac (honorable mention to Mad Maxx with Blitz as well).