Strength of schedule is calculated from the opponents projected fantasy points allowed for the PK 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.
Nedney won't be projected to be a top kicker by many. He is an adequate kicker that is reliable but not a difference maker. The inconsistent wind conditions of San Francisco have not been a factor for him. The 49ers have a fairly easy strength of schedule so if the offense improves he might be worth a look.