If an organization wants to make a trade after the July 31 deadline, they still can - it just becomes more complicated. It's harder to trade with one specific team, there's more risk involved, and it can be quite tactical as teams have the opportunity to interfere with rival clubs' plans.
It all starts by a team placing a player on waivers. In many cases a club will put players on waivers simply to judge interest, and will pull him off of waivers if/when he is claimed. But we'll get back to that, so hold that thought.
Think of waivers as a list of every team in baseball. Every team has an opportunity to claim Player X, with claim priority ordered by worst record to best in the same league, and then worst record to best in the opposing league. Once a team makes Player X available to that list, teams have 47 hours in which to place a claim on said player. From here there are three options.
1 - No teams place a claim on that player
In this scenario, a player has "passed through waivers" and his team would be free to trade him with any other team in baseball. He can be traded for A) 40-man roster players who have also cleared waivers, or B) non 40-man roster players.
2 - One team places a claim on the player
The two teams have 48.5 hours to work out a trade. Alternatively, the claiming club can pay a $20,000 fee and assume the player's contract if the original team is motivated to just dump a contract (or player) on somebody or anybody. This can happen if the two teams cannot work out a trade and the original club does not withdraw the waiver request.
3 - Multiple teams place a claim
In this scenario, precedence goes in the order outlined above. If Player X is placed on waivers by the Red Sox and there is interest shown by the Tigers, Twins, Pirates, and Giants, the Tigers would have priority over the Twins, who would have priority over the Giants, who would have priority over the Pirates. Again, once the claim has been awarded the two teams have 48.5 hours to work out a trade. Or, as in case number two, the original team can stick the claiming team with the player and his contract.
Why do teams place players on waivers?
- To judge interest.
- To trade the player.
- To dump salary.
- The team actually has interest in acquiring the player.
- The team is trying to block a competitor from being awarded the claim, in which case the claiming team usually believes that Player X will be pulled off of waivers. Of course, as mentioned, this is also how teams can get stuck paying salaries they did not actually want to take on. Even if a deal can't be worked out, the original team can just stick it to the claiming team.
- The original club was gauging interest in the player and had no intention of actually trading him.
- The original club does not want to send the player to the team awarded the waiver claim.
- The original club and the claiming club cannot work out a trade.
All in all, to summarize:
- Nearly all players are put on waivers in August.
- Not all players on waivers are placed there with the intention of being moved.
- Teams with worse records have priority over teams with better records, American League teams have priority over American League players and National League teams have priority over National League players.
- Teams can make a claim on a player to block a rival club from being awarded the claim, but this is dangerous because the claiming team could just get stuck with a player they didn't want...and his salary. It's why Ricky Nolasco would probably clear waivers: nobody wants to take on his contract.
- If a player clears waivers they can be traded to any team for a player who has also cleared waivers or for non 40-man roster players.
- If a player is claimed he can only be dealt to the team awarded the claim.
- A player can be pulled off of waivers once, but if put on a second time the waiver request is irrevocable.
- Players with no-trade clauses can still block a trade.