Knifing the air lowers your accuracy.
I never knifed the air in any of the MOABs I earned. The hate mail, praise, friend requests, shocked squealing from younger players, and half of the lobby being emptied after the game is over; all of these make up for it for me.
I think any decent player can earn a MOAB; it just comes down to four things for me:
- Having a decent connection to the host
- Your teammates are positioned well across the map (preventing stupid spawning)
- Knowing where your teammates are (therefore predicting where the enemy players are)
- Having teammates that are good enough to hold their own, but can't exactly earn a MOAB, themselves.
Only 8 times have the above conditions been met for me (meaning 8 MOABs), but that's fine, because there's only 8 Online Vault slots.