To boost this, find an empty lobby or create your own room under Xbox Live > Community > Lobby. You'll want to set it up so that the losing team is the Legends and the winning team is any minor league team.
The Legends should pull their goalie and let the minor league team score 1-4 goals. Play out the entirety of this game, as you stop earning points if too many wins come from disconnects. Best way to make it go by quick is to have someone win the faceoff, follow the human-controlled player into their end, and just sit there to keep the clock running.
For games two through four, follow the same instructions, but the Legends quit out after two or three minutes of gametime, or once the clock is under 17:00. You earn less points for each subsequent game against the same person with points stopping altogether around the fifth game, so you'll need several people to reach 25 this way.
Rank does not seem to affect this very much; following the above earns you around four or five levels per person.