That is pretty crazy, I've looked at that box score for a bit, and the only very slight difference between the two is your C had 2 turnovers, and the opposing C had 1 turnover, then the opposing C had 1 more offensive rebound.
Then they both played the same minutes, had the same amount of points, and your C had 1 more of total rebounds.
I've never understood how the game rating gets calculated, but it would definitely be interesting to read. It would be odd if singular stat categories were weighted heavier than others, to the level where a difference of 1-3 between two players with similar stat lines in a game, might end with a similar 15.0 vs 12.5 rating.
Balls of Steel, your team is pretty tough, and for us both being the same record at this moment your team is stronger than we are. Nice job building that team.