You know that trades can be made after July 31 by acquiring waivers on players. How is this done? The explanation is below.
Though the July 31 non-waiver trading deadline has passed, teams can -- and some surely will -- make deals through August 31 (the deadline for placing players on postseason rosters) or even in September (to get help they might not be able to get otherwise).
"Non-waiver" is the key to all of this; waivers must be obtained on players that teams wish to trade. Waivers can be requested on players throughout the season; these types of waivers are described in the table below, which is courtesy of this excellent explainer from our SB Nation Blue Jays site, Bluebird Banter. The waivers required for deals made past July 31 are "Trade Assignment Waivers":
| Type | Function | Revocable? | Price | Periods Available | Period Effective | Ineligible Players |
| Trade Assignment Waivers | To assign a player on the 40-man roster of one MLB club to the 40-man roster of another MLB club. | Y* | $20,000 | 3 pm CT July 31 through the last day of the season | Rest of period | Disabled†, Military, Ineligible, Voluntarily Retired, Bereavement, Restricted, Suspended, or Disqualified Lists |
| Outright Waivers | To remove a player from the 40-man roster and assign him to a minor league club. | N | $20,000 | (1) Nov 11 - Feb 15 (2) Feb 16 - 30th day of the season (3) 31st day - 7/31 (4) Aug 1 - Aug 31 (5) Sept 1 - Nov 10 | (1,2,5) Rest of period or 7 days (whichever is first) (3,4) Rest of period | Disabled†, Military, Ineligible, Voluntarily Retired, Bereavement, Restricted, Suspended, or Disqualified Lists |
| Optional Waivers | To assign a player to an optional assignment in the minor leagues (without being removed from 40-man roster). | Y* | $20,000 | (1) Feb 16 - 30th day of season (2) 31st day - 7/31 (3) Aug 1 - Oct 1 | Rest of period | Players on lists above†, plus ones who are less than three years removed from the date of first reporting to an MLB team (optional waivers not required). |
| Unconditional Release Waivers | To terminate the relationship between an MLB player and the club and make him a free agent. | N | $1 | All times | Immediate | Military List, Ineligible List |
* When a player that was previously pulled back from revocable waivers is placed on the same type of waivers during the same waiver period, that waiver request becomes irrevocable. That is, a player who is placed on waivers may only be pulled back once.
† Outright, optional, and trade assignment waivers can be obtained for players on the disabled list only if: a) the minimum period of inactivity (15 or 60 days) has elapsed; b) the assigning club guarantees the player is well enough to play.
So if the Cubs wish to trade, say, Nate Schierholtz or Edwin Jackson, or anyone else on the team, here's the procedure they must follow, also from the Bluebird Banter article:
- Club registers a request for waivers with the Office of the Commissioner
- Notice of waiver request is given out on a private channel to all major league clubs
- Other clubs have two days to submit a claim
- If a club claims a player on revocable waivers, the Commissioner will automatically revoke the waiver request unless the club notifies his office that they do not wish a withdrawal.
- If there is no claim, the after two days, the player "clears" waivers and can be assigned or released. If there is a claim, the player is granted to the team with the highest claiming priority.
"Highest claiming priority" for August trades goes first to teams with the worst records, in reverse order, in the trading team's league, and then to the other league. As noted in the Bluebird Banter post, this is why you see more intraleague deals after July 31 than interleague swaps.
A reminder, this means that just because you hear a player has been "waived," it doesn't mean that player is going to be traded. As noted above, this is supposed to be on a "private channel" -- but often, that "private" word goes public, and Twitter comes alive with breathless "Soandso has been waived!" tweets, which mean virtually nothing. There's a reason these types of waivers are called "revocable" -- it means, as shown, that those waivers can be revoked unless the team in question says to the claiming team, "Here, he's yours," as happened August 10, 2009, when the White Sox claimed Alex Rios from the Blue Jays and Toronto simply let the Sox have his contract.
"Assigned" as stated in the procedure above means, effectively, the waiving team can then trade the player ("assign his contract" is the official language used) since he has cleared waivers.
Thanks again to Bluebird Banter for the table and the explanation. Hope this makes it easier for you to understand how trades go down in August.