It isn't bug, it isn't even close to bad luck. BBstats were 140 vs 134 (You were better), but it's very small difference (one sublevel in every statistic). And we have to remember that stats of opponent were decreased in Q4 because of garbage time and worse players on court. So we can assume that before garbage time opponent's BBstats were at least the same as Yours or even better.
Similar BBstats + HCA + more effort in most cases means victory.
It isn't easy to win first game in season when it's away match. GS is the same, enthusiasm the same (and in most cases lower than in next games) and therefore HCA has bigger effect than in further part of season.