I am going to start calling this the 'west ham paradox'
Namely, why is it that we smashed west ham all the time when we weren't that good, but as when we got better we started having more problems with them?
Since we first got champions league football (2010/11 season) our record has been W8 D3 L8. For what is a mid table team, that is pretty pants. Our only league double in that time was 2012/13. In 2013/14 we lost three fucking games against them. Not to mention that the 2-3 victory in 2013 and 2016 required last minute winners in games we were losing, and the 1-0 win at upton park in 2014 was a late winner after they missed a penalty. The 2-2 draw in the home game that season required a last minute goal to avoid defeat, as did our home draw last season.
I think it's a case of asymmetric pressure. We have little to gain by beating them (it's expected) and everything to lose. On the other hand they have little to lose and everything to gain, given that the players know that getting one over us tides the fans over. It's the same reason cupsets tend to happen.
I also suspect the west ham players have our number. They seem to know that if they keep us scoreless for long enough we will panic and give them an opening.
For these reasons i utterly hate it when we play west ham. Maybe this is how Woolwich felt about us when we were shit. One of the difficulties of getting better as a team is that the dynamic between rivals shifts. I've noticed that in the three seasons leading up to us finally finishing above Woolwich we didn't lose a league game against them. Since then we've lost two (nearly three) of the four we've played, despite going into each of those games as clear favorites.
I'm not saying this is a hard and fast trend, but i'm not sure if we really know how to play as favorites yet. Particularly in situations where the other team has little downside and huge upside. Something to work on for next season.