5.5 on the OS scale is average. Unlike most review sites - a 5 on a scale of 1-10 is right in the middle instead of a 7 being average and everything under that being terrible.
A broken game with tons of glitches should be a 0-3.
Anyways - features should always be part of a review, especially when the features are limited. You can talk about how fun a game plays, but when play nows get boring (and they will) then what? Be a GM is there but there's no minors, no draft [yet]. Be a Pro is there but you can't sim to your next shift which means you get to watch the AI fuddle around.
Features and gameplay should be reviewed together. If a game has unreal gameplay but limited modes that keep the game from being fresh then that should be a factor just as a game with 100 modes and ****ty gameplay should be a factor.
There was a big anticipation for NHL 15 and it fell flat for a lot of people because of the important modes being left out for what many perceive as fluff (billowing jerseys, a million different fan models, etc).
I think 5.5 is a fine score because this game is average. It does things well and it does things poorly (because of modes being omitted). Again - a 5 is average and that's what NHL 15 is. It is average.