IMHO, you continue to be WAY LOW on a lot of veteran producing RBs (Willis, Sproles, Lynch, Torain). While this is a dynasty league and the future is important, it is NOT more important than winning this year. When an injury or bye week comes, I'd much rather trot out one of those 4 RBs than Carter, Helu, or Hunter.
While that may be true, you should always have enough depth anyway. Would you seriously consider trading Carter, Hunter or Helu for one of those veterans. I can only see Sproles being worth it since those other guys are just stop gap options for their NFL teams and should only be looked at that way for your dynasty roster as well.
In most startup dynasties over the offseason, Lynch was going before all 3 of those rookies. I would without a doubt rather have Lynch currently than those three. Sproles isn't even a contest, and Willis I would also insta-accept for either of the three. I'm not sure what to make of the Redskins and Torain...but if I had to choose between Torain and Helu, I'll take the guy that has shown some ability to be a feature back and is currently starting.
So are a few mediocre to good games from Willis McGahee or Marshawn Lynch worth a potential long term starting RB? If you have to rely on those veterans you're probably in some trouble anyway.
First, I think you are being disingenuous when you say "a few mediocre to good games". In a traditional 12-team league, Willis is an every-week starter for 80% of fantasty teams. Despite having an awful schedule and few games to start the year, Lynch is a top 25 RB in scoring in my PPR league.
While fantasy owner perceptions will often lie, the numbers don't -- Willis and Lynch will/should likely be in owners starting lineups fairly often, especially considering bye weeks, injuries, and matchups.I'm not willing to give up the points lossed by starting some teams backup, and risk dropping a game that could keep me out of the playoffs.