I tried this for the first time at the 2 spot in a 12 franchise QB heavy 1 keeper league (15 roster spots). Starters 1 QB, TE, K, DEF...2 RBs, 2WRs, 1 WR/RB flex. This is what I wound up with:
QB - Luck
RB - Ivory, Stewart, Crowell, David Johnson, Matt Jones,
WR - Cobb (K), Hilton, Evans, M.Bryant, Marvin Jones, Doug Baldwin
TE - ASJ
DEF - Buffalo
K - Folk
Unsurprisingly, the spray and pray left me with no depth outside the heavy skill spots. TE will have to be a week to week waiver wire scrounge. And I will have make some magic happen WHEN Stewart gets hurt. But like you said, there are always a few gems waiting in the wings as the season develops.
All in all, it felt bizarre waiting till round four to pick up a RB.