When my promised-start guy missed just 1 start (had him 3rd LB in depth chart in a 4-3 defense and the 4th guy actually passed him in stats over the first 5 games of the season and moved up on the depth chart) his WE took a ~20-25 point hit and it took 3 games of starting him to again for his WE to move back to roughly where it was before, although it was still a couple points lower than it was initially. So there's a decent chance that your guy's WE takes a big hit as well just from one missed start and may end up with the reduced WE for the duration of the offseason. I'd be interested to know how it goes for you if you do decide to sit him.