Major League Baseball has proposed a three-week free agent signing window in December, sources confirmed to ESPN, as part of a plan to generate an offseason transaction frenzy similar to those in the NFL and NBA.

MLB wants free agency to officially begin on the Monday of the winter meetings, which take place in early December. The window to sign players would close on Dec. 21 and then reopen on the first Monday in February before spring training starts. There also would be a ban on all trades during the gap between those proposed free agent periods. Teams would still be able to negotiate with players starting five days after the conclusion of the World Series, but agreements could not be finalized until the winter meetings.

The proposal comes as part of negotiations for a new collective bargaining agreement, and only as part of a salary cap system, which MLB has previously expressed a desire for. The MLB Players Association said in a statement Thursday that the latest proposal of an "artificial" free agent window "would reduce player leverage and create a game of musical chairs pitting player vs. player."

In addition to the change in the offseason calendar, MLB also is proposing the use of weekly rosters, which teams would set between Sunday night and Monday afternoon. All of the moves are intended to combat roster churn, which has become the norm in order for teams to have fresh pitching arms throughout the season.