Strength of schedule is calculated from the opponents projected fantasy points allowed for the DEF 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.
The Jags have gotten the safety they so desperately needed (Cyprien) and retooled their secondary as best they can. The problem is it still looks relatively threadbare, with their secondary looking only marginally more promising than their QB situation. It's only a workable "Front 7" that elevates them above the rest of their peers.