OK, so that's a different measure just using a team's YTD winning percentage, where FanGraphs says they use the opponents' forward looking projections.
If we're using Fangraphs to project playoff percentages it seems we should use their SOS projections too.
Either way, the schedules are close, but the tougher part of the Brewers schedule is in the next two weeks, but the Cubs schedule is tougher in the last week using these measures, mainly because of their games against the Braves.