- If a player is traded, the players recieved still count for the team. A good example of this would be that Zach Miner, who came over for Kyle Farnsworth is still counting for the Tigers in the Kyle Farnsworth for Scott Moore deal. I understand that it is unfair to assume that a player would still net the same value, but I did this for fun to look back at old trades.
- Players are credited if they leave via free agency, netting a compensation draft pick in return.
- A player's value is only counted until they become a free agent. Frequently, players re-sign after hitting the free agent market, but I am assuming that the player could be signed by anybody during that time. If a player re-signs before declaring free agency, I am counting their contributions during the next contract.
- In the case of players dealt in subsequent multi-player deals, the value they contribute is the percentage of contribution to the team traded to compared to others. That sounds confusing, I'll provide an example.
The first trade I'll show is the trade in July of 2002, where Jeff Weaver was traded to the Yankees, who traded Ted Lilly, John-Ford Griffin, and Jason Arnold to Oakland, who in then dealt Franklyn German, Carlos Pena and Jeremy Bonderman.
You can see that the Tigers appear to be the clear winners of this deal. This is, of course, before I factor in the business side of things. It's very possible that the production early on helped the Yankees and A's in their playoff runs, although that could be offset by the superb season Bonderman had in 2006.
The Yankees appeared to be the winners of the deal in 2002. Jeff Weaver posted a 2.4 WARP for the Yankees that season, but fell off the planet the next season. Ted Lilly and Erubiel Durazo (acquired for Jason Arnold) led the way in 2003, while Weaver struggled. The Tigers got contributions from all three parts of the trade that season, but it didn't do a lick of good. After 2003, Jeff Weaver was dealt for Kevin Brown, who had one solid season before injuries ended his career. Ted Lilly was dealt for Bobby Kielty, who ended up being a fourth outfielder before being released in 2007. You may wonder where Oakland got value last season. John-Ford Griffin was traded to Toronto in 2003 for Jason Perry, who was then dealt back to the Tigers last year for Jack Hannahan, who provided the production for the A's in 2007, and still will. Hannahan and Bonderman are the only assets remaining from this deal.
This next deal is rightfully regarded as Dave Dombrowski's best as Tigers General Manager. In January of 2004, the Tigers acquired Carlos Guillen for Ramon Santiago and the other Juan Gonzalez. While both Santiago and Gonzalez were released by Seattle to be later re-signed by the Tigers, Guillen has blossomed into a star:
The final trade I'll look at is another winner for the Tigers that happened all the way back in 1991, when they acquired Mickey Tettleton from the Orioles for Jeff Robinson.
I have accumulated the data for every trade since 1983 where the players involved combined for at least 1 WARP after the deal. If you have any trades you are curious about, please let me know and I'll post them the next time around.