I'm not sure why they call it an efficiency rating, because that is clearly not what it is. It seems more like a contribution index, in that more you do, the higher your score. For example, if one player shot 3-4 and another was 5/10, all other things being equal, the 75% shooter would have a lower efficiency rating!
3/4 would be 6 points and 1 miss, so that would be +5 (6-1)
6/12 would be 12 points and 6 misses so that would be +6 (12-6)
Here is the full equation: = PTS + REB + AST + STL + BLK − Missed FG − Missed FT − TO
It rewards stat stuffers, even if they aren't necessarily efficient.
I'm not sure how McBride did not impress you. Judging by her box score, she was very efficient. She shot 50% (both attempts were 3's), added an assist, had no turnovers, and her 5 boards were just 1 below the team-high 6 (attained by both Nneka and Maya), despite playing under 11 minutes. Since we can only go by the box score, I think she did very well. Skylar's numbers are nice was well, as far as true efficiency is concerned. Of course if we had video, we'd know so much more about everyone's performances, like how many passes should have been assists but were flubbed by the shooter or drew fouls that sent the shooter to the line. We'd know how many fouls were committed to prevent an easy basket because someone else got beat off the dribble. I hope tomorrow's scrimmage is streamed, but I am not confident it will be.