Strength of schedule is calculated from the opponents projected fantasy points allowed for the WR 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 best thing that could have happened to Nelson in the off-season was the Packers re-signing free agent wide receiver Randall Cobb. With Eddie Lacy in the backfield and Cobb on the other side, opposing defenses can't sell out to stop Nelson. According to coach Mike McCarthy, Nelson underwent surgery to "clean-up" his hip after feeling some pain at the Pro Bowl. The surgery is considered minor and Nelson is expected to be fully recovered long before the start of training camp. Nelson will be 30 by the start of the season and it shouldn't be surprising to see him start to take a backseat to Cobb over the next season or two.