I would agree with a few others above,
Williams is last because of the injury, the match-up and the quarterback.
Amendola is a solid second choice as a result of the PPR nature. (upside here) [19 targets last week]
Ryan Torain against an almost mediocre run defense in the Colts is the best pick.
I Always go with a 20x touch RB over a solid WR2 on any given Sunday in my Flex.