The best and most productive RBBC for last year was probably Bush and Bell. Bell was anywhere from a low RB1 to high RB2, depending on size of league. As you have pointed out, we haven't seen a lot of instances where the RB with a less prominent role in the RBBC repeated that, so you thought based on that past track record, Hill would be lucky to do it once and than it might not be repeated again.
There can be different reasons that one or both members of a RBBC haven't repeated historically.
You're welcome to bet against any trend you want, but don't call me out for citing the trend. We're talking about making good, informed decisions. Everyone who bets against a trend has a list of reasons why this time is different. DeAngelo and Stewart owners thought that was the best backfield in the NFL by far. So did the GM. He bet his job on it and he's gone now.Is it possible for Hill to put up good numbers? Sure. Is it possible for him to do it more than once? Absolutely. Any time this situation comes up, I'd bet against it. More often that not, I'll be right.
Up to this point, I hadn't read your latest posts, in which I appreciate the tone (though confess to being no closer to agreeing with your overarching principles). I take that as a positive step, communication-wise. So, not to dwell on the negative, but in the interest of future postive communication, rather than characterize the discourse and couching it in adversarially loaded terms (confrontation, calling out, etc.) lets just mutually resolve to think of our exchange as, you think stuff, and I think stuff. You write stuff, and I write stuff. You may disagree with me, and I may disagree with you. It isn't personal (or certainly doesn't need to be). It is possible to have an exchange, disagree, but do so in a dispassionate manner. I honestly didn't think I was being disrespectful in broaching the subject about a seeming first round assumption upthread, it had come up a lot in the thread, far more than examining him as a second rounder (which he seems to be more commonly, if the thread responses are an indication), and I thought it might be causing a lot of mischief, even if unintentional, and the source of some confusion, misinterpretation and miscommunication in the thread. In fairness, multiple people have expressed confusion on this issue, it wasn't just me.
Part of making a good, informed decision, in relation to trend analysis, in this instance, is to examine and explore how a particular is similar to, and different from, the general. Obviously if someone is laboring under the illusion that a situation is different when it is the same, that wouldn't be conducive to understanding it. Lets look closer at Williams and Stewart, to see to what degree it resembles Bernard and Hill, and how it might deviate in important ways. In some ways, it is an excellent comp, probably one of the best, in terms of what they at one time (which seems like a long time ago) represented, an appealing convergence of youth, pedigree, talent and run scheme. What I mean by pedigree, BTW, is CAR has two first round RBs, and CIN has two second round RBs (round denotes their pedigree, a higher round is a higher pedigree). How might it be different?
If Hill is to Stewart as Bernard is to Williams, if Hill suffers from chronic and debilitating lower body injuries (feet, Achilles tendons, ankles, hamstrings), that is clearly going to be problematic for his outcome in upcoming seasons. But I'm not predicting that. Are you?

If Dalton improbably scores 28 rushing TDs in the next three seasons, that also will be problematic for Hill and Bernard. But, and I think I can speak for you here, we don't expect that to happen. There are no doubt other variables in which they are more similar in some ways or more different in other ways, but the above two came immediately to mind and I'd contend are potentially critically important differences betwen the CAR and CIN backfields. So while you intended this as a specific example of a general point that RBBCs are intrinsically (?) inferior and hard to repeat, I am left thinking CIN/Hill is more likely to beat the odds if Hill isn't chronically, habitually injured, and in effect, something on the order of Newton/Tolbert's 48 rushing TDs were injected into the 20 scored by Williams/Stewart since 2011 (this is a case where CIN won't be exactly like CAR, so maybe better to think in terms of what CAR could have been - needless to say, without Newton, no guarantee they would have been around the goal line as much, but CIN is an example of a QB that moves the ball without stealing an inordinate number of TDs from the RBs). This also raises the cautionary tale that if CIN employs a Tolbert doppleganger and turns the RBBC duo into a three headed monster, that blows up Hill's projections. That could happen with Law Firm this year, I'm not expecting it, and I don't make dynasty decisions based on just the current year (arguably to a fault). Ideally I'd try to position rosters to be competive in the present and future, but that can be difficult to strike an exact balance on, so I have been known to weight the future on the rationale of sheer numbers - there is more of it.

In other words, I might trade for a WR like Patterson or Watkins or a TE like Ebron, even if it weakened the roster this year, if I thought it would make it stronger in the next 3-5-? years.
But I digress. Back to CAR and CIN RBBCs. CAR scored 68 rushing TDs since 2011. Nearly 23 per year. If the bulk of those had gone to Williams and Stewart, we would probably think of them more favorably (and if Stewart hadn't been hurt and added in 1,000+ yards per season). But even if Stewart had low RB1 or high RB2 numbers, I suppose that would be a player you still would have no interest in because he wasn't "elite".
The CAR GM did get fired. I'm not sure anybody could have known how chronic, severe and debilitating Stewart's lower body injuries have become, so I can't fault him for not being psychic and avoiding drafting Stewart. That is regarding drafting Stewart. Later, I disagreed with how much cap dollars they have allocated to the RB position through multiple extensions, and think that was a mistake (I used to think most egregiously with the aging Williams, but with Stewart's lack of dependability, at least he has answered the bell the past two years - though they definitely had other options than spending a lot of money on three RBs), but that is somewhat afield from the primary discussion here. Not to mention, the success or failure of an overall roster involves a lot of moving parts, and is far more complex than could be reduced to the RB landscape alone, without also looking at the passing game, OL, defense, ST, draft, free agency and trades at all positions, cap management, coaching, player development, probably a thousand things.
Any time what situation comes up? There aren't a lot of exact precedents for the CIN backfield. You have cited in some cases the negatives about the situation (though interestingly, it sounds like we agree on Hill's upside, just completely disagree on the fantasy/dynasty relevance and usefulness of an approximately high RB2 player), surrounding talent, character/bad influences, capped upside barring injury, etc. But there are some positives. Pedigree (RBBC with two second rounders), youth (rookie and soph), potential top 5 rushing attempts scheme (new OC), an established passing game with a Hall of Fame caliber WR and above average regular season QB that will put the ball near the stripe more often than, say, JAX (if Hill had gone there), Hill having the size to have a legit shot at 50% or more of the carries (Bernard can still have more overall touches even with 200-225 carries, with 60-70 receptions) and DD TDs, and potentially for more than one season if he is given a defined role which makes that possible, etc. So again, how many counterparts are there to Hill, EXACTLY?
Bet against what? Hill being an elite, top 5 RB (from a low second draft pick?)? We aren't disagreeing with that. But as jurb noted, it may be an unrealistic expectation to get a high percentage shot at an elite top 5 RB 20-25 picks in the draft. You aren't saying it never is a good play to take a high RB2 depending on certain, particular roster compositions, so we don't disagree there. And I'm not saying it is always a good idea to take a RBBC back, we don't disagree on that. You have said you have no interest in a high RB2 because that is low upside in your book, and this seems to be based on your singular league experience noted elsewhere (? - which, if so, may put you at a disadvantage in having a sense of what may be a more typical league state of affairs and status quo for others) in which to be stacked a team has to have two top 10 RBs, and all teams are stacked = 24-28 RB1s in a 12-14 team league. I don't want to misrepresent what you stated, but I think I got that right. Obviously it doesn't add up, so I'm forced to conclude you are exaggerating, please correct me where my reckoning is off. Not trying to put too fine a point on things, but I think this is one area which brushes on some core, root, fundamental miscommunications, misinterpretations and misunderstandings. If we could make a clarification breakthrough on how there really aren't 24-28 top 10 RBs (by definition) which you seem to be inexplicably pointing to, and therefore what you DO mean by such statements, it would be very helpful to me personally, and perhaps the thread as well, to better understand your position. Or maybe not, the way things are going, not sure I'm any less stonkered than I was before.
One possible direction is when you mean stacked, you mean some rosters in your league are stacked at RB, some at WR, some at TE, and between them, one way or the other (maybe with dominance in 2-3 position groups), and they are all "stacked" in some way, not necessarily at RB. But if that is what you mean, it wasn't clear in the recent posts/exchange with jurb, and that is kind of confusing. In part this current thorny and knotty problem has gone into a rabbit hole morass we are getting deeper and deeper into, imo, because there is so much jumping around (not just on your part, but collectively, myself included), from first round to second round, what constitutes good value for that pick, does a RB taken with a low second need to be elite top 5 to justify the value of that pick, the specific and general, individual RBS and RBBCs, contemporary and historical, are we accounting for particulars of roster composition as possible exceptions for the GENERAL anti-RBBC strategy, are we jumbling together 12-14-16 team formats and crossing our wires on interpretations when we haven't even identified what the context is half the time and aren't even talking about the same thing without realizing it, what are expressions of an actual philosophy difference, or just personal preference, a bunch of other things, it presents difficulties for a group to follow along over a period of time if they are bouncing in and out and not reading the entire context (or even if they are, challenged to remember or keep straight everything that has been said, some of it seemingly contradictory).
As far as league differences, which can impress and form the idiosyncracies and peculiarities of each individuals background and history, my experience is more like jurb, in five leagues there might be a few teams that I would call stacked, but I'm in 12-14-16 team leagues, and it is easier to be more collectively stacked I suppose in a 12 team league, if that decribes your's. Obviously it isn't possible for every team to have Peyton Manning, Jamaal Charles, LeSean McCoy, Calvin Johnson, AJ Green, Demaryius Thomas and Jimmy Graham. I was in a league with a team or two like that, the only one before or since, it had a payout structure that favored the top two teams, and I left, not just because there was a team like that, but more having to do with the circumstances under which it was assembled. But that situation was far, Far, FAR removed from the norm of my experience.
At least I can now see how, to an owner in a league comprised of 100% "stacked" teams, whatever that means, it would be consistent for you to find the prospect of starting a RB2 prospect like Hill meager and pitiful in that context.
I'm less interested in whether you are right more often than not, than if you are wrong this time. There aren't 24-28 feature RBs that get all the carries, stay in on third down, block and catch and are designated goal line runners. I'm not seeing a convincing explanation that a high RB2 in a RBBC is a bad pick when MOST starting RBs fall into the category of RBBC, and most aren't top 10?
A quick observation about the length of time it takes to examine "recent" football history in which there is some depth, but not so far back that the game was so different as to make stats from an antiquated era of questionable value for the purpose of relating that to the contemporary situation in a meaningful way. Lets say we go back a decade, 10 years isn't a massive number in terms of statistical samples. If we are talking about the CIN backfield specifically, which, if not unprecedented, is probably rare (at least in the past decade), and there are just a few examples with many or most of the factors ticked off here, than a few times (2-3?) is even less of a meaningful and relevant statistical sample, I'm sceptical we can extract deep, enduring principles from such an insignificantly small sample. In that sense, I'm not sure what you are referring to in saying you are right more often than not. What if the CIN situation is so rare it has happened twice in the past decade (refer above to all the positves - CAR was close, but if you don't think 48 TDs are going to be scored in the next 3 years by the QB/FB, and you aren't predicting as checkered a medical record and injury history for Hill as Stewart, that has to be thrown out, if you do this exercize more than a minute, and while I'm not opportunistically putting on an anti-historicist hat due to the exigencies of the debate, you may find it is hard to come up with an EXACT ANALOGUE for the 2014 CIN backfield - and the less exact it is, the less likely it is to be relevant to the 2014 CIN RBBC), and you were right once before and are wrong this time. You are one for two. Were you right more often than not? To be clear, I'm not speaking of how you may have been "right" about less talented RBBCs, or ones in which one or both members were old, or not as talented, or injured, etc. I'm not interested in them. I'm interested in the CIN RBBC, THIS YEAR, and of course future years, too. IF Hill has 225-250 carries, 1,200-1,300 combined yards and 12 TDs in 2014 (not likely, but if), he is the goal line RB and the TDs look sustainable, and there aren't any critical material changes in personnel or scheme going into 2015, I'm not sure on what basis I would downgrade his next season projection? This is another in a cast of thousands of ways in which our thinking diverges.