The point I was making is that a lot of fantasy owners have "rules" based on history. A lot of fantasy owners believe that Detroit is terrible at drafting, and downgrade their draft picks as a result. A lot of fantasy owners believe that Shanahan loves churning late rounders, and grab a new flavor of the week every season (you see that cropping up again from the group discounting Morris and expecting him to be replaced by someone else). A lot of fantasy owners believe all WRs coming out of Florida are terrible. A lot of fantasy owners believe that the spread and the option are gimmicks and discount anyone who isn't a pure pocket passer. A lot of fantasy owners believe that anyone who gets 370 carries is destined to combust in the following season. A lot of fantasy owners believe Fox will never give a rookie carries over a veteran. These rules are always accurate... until they aren't anymore. Hell, most of these rules are probably good, sound positions that will yield a positive EV over a long enough timeline. They won't yield a positive EV in every single instance, though. Football is a complex system with an incalculable number of variables at play, and every situation is unique. History is invaluable for making predictions, but history should always be where we begin our analysis, not where we end it. History is not destiny.
In fact, looking back at Fox's history, we can see differences between this year and previous seasons. DeShaun Foster didn't receive a single carry his rookie season... because he was on injured reserve. His second season, he had to compete against Stephen Davis, newly acquired by the team. He lost that competition. DeShaun Foster's lack of early playing time wasn't because he was a rookie, it was because he was injured and then later because John Fox hand-picked another RB who happened to be better.
DeAngelo sitting behind DeShaun in 2006 is a little bit more damning, but still reasonable. DeShaun was a former 2nd rounder himself, one who the coaching staff had hand-selected and who they seemed to like (based on their willingness to keep giving him work even when Stephen Davis was playing great). DeAngelo did not dramatically outplay DeShaun in his opportunities to demand a bigger role (4.1 ypc vs. 4.0). And DeAngelo still got a third of the RB touches, including a team RB-best 33 receptions (still a career high). So, when Carolina had two hand-selected 2nd round RBs who were performing at equal levels, they preferred the veteran one. Stewart sitting behind DeAngelo is super easy to explain. DeAngelo suddenly became one of the best RBs in the entire league. He averaged 5.5 yards per carry. Despite that, coaches still liked Stewart enough to eat a substantial portion of DeAngelo's workload. Hillman sitting behind McGahee and Moreno is a lot easier to explain now that the coaching staff and front office have made it clear that they view him as a CoP back (both through their words as well as through their actions, most especially by drafting Montee Ball in the 2nd).
Montee Ball is a different situation. He's not really comparable to DeShaun Foster, unless you think he's going to suffer a season-ending injury in preseason, or Denver's going to spend big money to bring in a hand-picked free agent (Ahmad Bradshaw?) to compete. He's not really comparable to Jonathan Stewart, unless you think Knowshon Moreno is going to magically transform into a 5.5 ypc player who is going to top 1500 yards rushing and lead the league in TDs. Yes, there are still some troubling comparisons- DeAngelo's sophomore year, Hillman's rookie year (although, again, Hillman is a very different player). But by and large, Montee Ball is a different guy than the guys Fox has ignored in the past. He's not competing against hand-picked veterans that the coaching staff loves, he's competing against an inherited and underperforming Knowshon Moreno who the coaching staff has repeatedly and consistently given a vote of no confidence. He's not a 3rd down CoP back, he's a 2-down goal line back. He's the NCAA's career rushing TD leader, playing in an offense that scored the 3rd most fantasy points from inside the 10 yard line last year.
Knowing John Fox's history is useful, but John Fox's history is not Montee Ball's destiny. It's possible to acknowledge the risks, and still say "this situation is so different, and the upside is so valuable, that I'm going to take a chance on Ball, anyway".