Wow that was amazing!!!!
To have them lose after all this strong buildup and such an exciting game although it seemed so certain that they would win after all, is a really good decision!
It strengthens their resolve and determination during the next two games and is also a huge opportunity for growth and character development for the team (especially Sakuragi as the one who'll most likely blame himself the most; refreshing to have the MC make mistakes like that in the first place).
It also fits perfectly that Gori's dream can't be reached yet, after all (even if he was willing to "sacrifice" his foot).
If they keep on winning for the rest of the games it is a much more satisfying feeling- After having victory unexpectedly snatched away from them due to such a silly mistake even after everyone exceeded their personal limits as players and endured so much ~
I think pretty much all readers thought it was a shame for them to lose (even if you would've expected them to lose), so it makes us cheer even more for the characters and support their ambitions & goals.
I think letting them lose this game is a very effective measure!