Flex - Daniel Thomas @ Buf or Titus Young vs GB.
TE - Aaron Hernandez vs Indy or Greg Olsen vs TB
Indy is #1 against TEs, but if Hernandez plays, I dont know that I can sit him. Also, Olsen's performance is probably not repeatable.
Flex is the bigger question. GB/Det could be a shootout. But Young can get lost in that offense. Thomas has been taking on the majority of the touches and the Bills can't stop the run, but he's still in a timeshare and Bush could take back the top spot at any point.