What things do we know today that PFF is ignoring?
As far as I can tell we don't know that much. The coaches don't know that much yet. We can speculate all day on that, but Ota's are not training camp, training camp is not preseason, preseason is not the regular season.
I could easily see the distribution of rushing attempts being a 50/50 split between Anderson and Booker. But I would not expect that split to occur on a game by game basis. That is not how Kubiak or Dennison like to use their RB however. They prefer to have one do it all RB and even when they didn't have a good player like Portis, it was more of a running back by competition than by committee. Each RB got their chance to be the main RB until they got hurt or proved ineffective, when that happens, they move on to the next RB.
I would expect Anderson to start as the primary ball carrier with Booker coming in on passing downs. This will last for the first half of the season, or at some point where Anderson wears down, then Booker takes over the featured RB role.
So that 50/50 split may see Anderson being useful for the first half of the season, then Booker being useful for the second half of it.
There is always the chance that Anderson plays very well early on and maintains his role as the starting RB all year. He has not had over 200 rushing attempts in a season yet in the NFL or college level however, that may be a trend which continues.
Booker is a very good RB and Anderson is going to need to play at a very high level to hold him off in my opinion. So if Anderson does keep the job through camp, preseason and into the season, he should be very productive in those early games.
I think it is a matter of time before Anderson either gets injured, becomes ineffective (perhaps due to injury limiting his level of play, like last season) or Booker just out plays him in practice to a point where they have to get him more involved.
I don't know any of this however. I am just guessing at what might happen based on the information I do have.