Another possibility: According to statistics on NBA final games, the team winning the first game has over seventy percent chance to win the championship.
Since the series is referred to as "the finals" I think you need to have finals games. It's not the LAST game (the final game) but the entire best-of-seven series. Better yet, just say "finals."
CJ, can you help with this? I would write it as "has over a 70% chance to win the championship." Is the "a" wrong?
And just a logic note - It's not that winning the first game does