Major League Lacrosse announced some major rule changes in the off-season. The league will introduce a fourth long–stickman to play. For the first eight seasons the league operated, each team could only field three long–stick defenders on the field at a time. This rule was unique from the traditional men's field lacrosse rules played in high schools and colleges. The league will maintain the two–point goal and shot clock that differentiates Major League Lacrosse rules from high school and college lacrosse. In addition, the league announced that each team would be permitted to have one additional roster position to a total of nineteen players.
The Rochester Rattlers' roster and staff will be transferred to the new Toronto Nationals team; however, the name, colors, and history are staying behind in Rochester to be potentially used by a future MLL team.
Casey, Ryan, and Mikey Powell, three of the best and most popular players in the league, all sat out for the 2009 season. The three brothers did not report to their respective teams as of the April 1st contract deadline - which means they are ineligible to play for anyone for the remainder of 2009. This was not the first time the Powell brothers sat out a season. The 2009 season was Mikey's third sitting out, while it is Casey's second, and Ryan's first.
The 2009 New Balance MLL Championship Weekend took place on Saturday and Sunday, August 22 and 23 at Navy-Marine Corps Memorial Stadium in Annapolis, Maryland. The two semifinal games were at 12 PM ET and 3 PM ET on Saturday. The Toronto Nationals and Denver Outlaws won their semi-final matchups and in the Championship game with 45 seconds left, Shawn Williams scored to give the Nationals a 10-9 lead and Toronto won the MLL championship.