You're right, certainly subjective. If you only watch one team regularly (not saying you do), it's hard to discern how that team's average effort level compares to other teams' average effort level. Living where I do, I see a lot of Bruins games, and it seems they are more consistent in their level of effort on a nightly basis. But they're on a 4-game skid, so...
And I also find it difficult to determine how much is due to effort vs. talent.