There are games that I lose, or that my ally loses, or that my crew lose.
Then there are games that the enemy wins.
If I feel like I was playing reasonably well, my crew was relatively competent and my ally was at least half decent, then it's the enemy team that won.
If I'm having a really off night and am just playing badly, then I lost.
If my engineer is shooting mortar shots at an enemy ship that has its armor up and neglecting the completely dead balloon despite me going "Balloonballoonballon!" over comms, then my crewmember lost.
If my ally is just incompetent, they lost. Likewise if they forced me to start up by not unreadying long enough for me to change my loadout (seriously, 30 seconds from deciding to captain to having a ship that flies well versus all of the appropriate loadouts and having my crew properly equipped is not enough time.)
If anyone in the lobby was incessantly asking us to ready up, they lost. It doesn't matter what team they were on, so far it's been held true 100%.
If my ally or myself made a poor decision on ship or loadout in response to the enemy team's setup, or ready without a full crew or with the wrong crew composition, the match was lost before we even made it past the lobby.
All of these work in reverse. 5-4 wins are much more satisfying than 5-0 wins, and when I've got an entirely crewed team versus a pilot, an offline pilot, and two gunners... well... the game ends fast but I don't feel particularly victorious.
[Also: If my entire team is having repeated disconnect issues on a tournament match that I'm subbing in, then I blame Muse.]