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 worst thing that you can do come draft day is pay for last season’s numbers and that’s what fantasy players did last season when they drafted Nelson. After scoring two touchdowns in each of his first three seasons, Nelson had 15 in 2011, and was the next big thing come draft day 2012. With a slash line of 49/745/7 in 12 games Nelson killed many a fantasy team. If you can get Nelson as your WR3 then you will have done well.