Defensive play is where "expected" analytics are more valuable when it comes to "what happened" because it HELPS isolate for goaltending performance. In this case, Jack Campbell mainly. The same thing is basically happening with McDavid this very season.
When it comes to offense, elite players are typically going to outperform expected for metrics.
As a result, if I'm looking at, say, a RAPM chart, I'll typically give most importance to the GF/60 and xGA/60 bars (about equal importance, maybe slightly more to GF/60 for forwards and slightly more to xGA/60 for dmen), followed by the xGF/60 bar, then there's a gap, and then there's the CA/60 and finally the CF/60.