Take a look at the third game, for example.

I would say MVP executed about as well in teamfights that game as Tempest did. But they won only two teamfights, and those were very marginal victories with just one kill each and no real further significance.

There were many fights that game where MVP were, mechanically and in terms of coordination, a little sharper than Tempest... but they were fighting down numbers, down levels, and/or down talent tiers. They weren't enough better in those fights to make up for the hole they started in. First shrine, Sake got picked as it started. Second shrine, they fought 3v4 while Merryday and Rich were against Lockdown top lane to try and prevent level 10 for Tempest. Rich got picked in between shrines, which gave Tempest a full level + talent tier edge for the third shrine. The two teams traded almost evenly over that shrine, with the level + talent edge of Tempest putting them slightly ahead. When MVP kept trying to force a win anyways in that fight, they ended up feeding multiple deaths as well as giving up the Punisher. Merc camp clash (and MVP's last major chance back into the game) saw Muradin survive only because of a 2-level scaling advantage, then Sonya die only because of a 2-level disadvantage. Between shrines, Rich gets picked top then Merryday dies trying to save him. They were forced to concede the fourth shrine due to massive level + talent tier gap. In the ensuing defense, Punisher roots plus level gap gave Tempest the edge they needed to get a keep. When MVP caught Muradin out and started off a teamfight with a large edge, Anub'arak's Hardened Shield talent and level 20 v 18 let him tank long enough to let Tempest disengage with only Muradin dead rather than it turning into multiple kills. MVP Black are forced to position aggressively to contest the fifth shrine despite being level 18 v 20, which leaves them vulnerable to Falstad forcing a hard engage with a Gust.