Trust me as an MD who practices musculoskeletal medicine: his injuries are flukes and not a sign of lack of durability. It may be true that he is fragile, but there is no evidence to support this notion at all, IMO.
I do think Felix needs to be in there a minimum of 50% of plays because I really bellieve his explosiveness and versatility is what this offense needs to get it to the next level - where the Saints and Chargers are. He spreads the defense horizontally because they have to respect his ability to turn the corner. He also forces the safeties to inch up because they don't want him to get on them with an open field and a full head of steam. He forces the LBs to delay their drops because they want to make sure Felix isn't coming on the draw. This is the threat we have been lacking in the running game to really make the passing offense go. These changes the defense has to make will create room for Witten and Austin to do their damage.
Now just when the defense sees it is a pass and they are rushing to get into position for Witten and Austin we can unleash Felix on a swing pass or circle root when he gets isolated on a LB. Or if the rush is too strong, drop it off to him on a screen.
I like Barber and I think he has a role here so long as there is no salary cap and Jerry is content to keep paying him $8M/yr but he needs to be used as a situational RB. I really think we are better off with Felix and Choice getting the majority of playing time with Barber in at the goalline, short yardage and closing out the game with physicality.
Garrett just needs to be bold and courageous and make the change. Yesterday was a good start but I want more Felix and I want the gameplan centered around him with Austin and Witten feeding off the opportunities he will create.