Strength of schedule is calculated from the opponents projected fantasy points allowed for the LB position. The best rating is +16 which gives the player the advantage against the defense and indicates an easy opponent, the worst rating is -16 which gives the defense the advantage and indicates a tough opponent.
There's good news and bad news where Vilma's IDP prospects are concerned in 2013. The bad news is that the Saints are switching to a 3-4 defense this year, and the last time Vilma played in that formation it was a disaster. The good news is that Vilma is slotting at WILB and wearing the 'green dot', which indicates a three-down role. There's some fantasy upside here, but not enough to justify investing significant draft capital.