The last day of July always marks the end of the Major League Baseball trading deadline and the beginning of deals conducted through waivers.
To explain, Any player under contract may be placed on "the waiver wire" at any time during the regular season. After the July 31 trade deadline, though, and on through until end of the season, a team must place a player on waivers if that player is to be moved to another team.
If a player is waived, any team in the majors may claim him. If more than one team claims the player from waivers, the team with the weakest record in the player's league gets preference. If no team in the player's league claims him, the claiming team with the weakest record in the other league gets preference. In the first month of the season, preference is determined using the previous year's standings.
If a team claims a player off waivers and has a viable claim as described above, his current team (the "waiving team") may choose to arrange a trade with the claiming team for that player within two business days of the claim; or rescind the request and keep the player on its major league roster, effectively canceling the waiver; or do nothing and allow the claiming team to assume the player's existing contract, pay the waiving team a waiver fee, and place the player on its active major league roster.
It really becomes a game of strategy within the game of baseball at this point, as teams try and upset the deals of rival teams, or try and manage their salary restrictions through waivers.
Look for teams like the Philadelphia Phillies and the San Diego Padres to make deals using the waiver process this season.
The Phillies did nothing before the trade deadline and are stuck with an old team and huge salaries. Although there was lots of talk about deals, nothing got done and the Phillies remain in the National League East cellar. If nothing changes before next year, then they will probably stay there, too. Look for Marlon Byrd, A.J. Burnett, and Jonathan Paplebon to be waived before the season is out.
The Padres made some deals, but they have more to unload as they get it together for next year. Look for Joaquin Benoit and Ian Kennedy to end up on waivers before the season is over, too.