1) LAG.
Lag is the biggest factor in online MK2. It blows my mind how many people from South America/Europe with red connections on MKAK, keep trying to join my Public Lobby. In a time-sensitive game like MK2, lag is a giant handicap, and HUGELY annoying. Sorry guys, I don't play anyone with Ping over 150, and definitely not over 200! It's not even MK2 in those conditions.
2. CHARACTER MATCHUP.
MK2 is very unbalanced in that Top Tier destroys Bottom Tier. Very few matchups are dead even, and knowing each one is so important. How many people counterpick my Mileena with Sub-Zero? A lot. You've gotta know Sub-Zero has no chance vs a tough Mileena. Raiden vs Shang? Shang eats through Raiden pretty easily, so knowing what Raiden must do to win, gives me a good advantage and the confidence to win a very difficult match.
3. OPPONENT.
The fun part about playing new people, is testing the waters early to see how good they are. You anti-air my Kitana 1st Round, and I know I have to play a little smarter to win. Obviously you go into a match differently against an elite player, than against a noob.