A rough estimate of Justin Upton’s trade value

In the comments awhile back we were talking about the Cubs possibly going after Justin Upton. GW wrote about Towers postseason press conference in which he identified 3 areas the Dbacks will try to get better at. GW said this:

The article also confirms they are trying to make room for Adam Eaton in their starting outfield, leaving Kubel, Gerardo Parra, Chris Young, and maybe even Upton as potential trade bait. If the Cubs were willing, I think a Castro/Garza for Upton/Corbin framework would have legs.

I had intented to write this much sooner than I actually did, but like the Cubs, I'm just not very good. I was curious what Upton's trade value might be. Prior to the 2010 season, Upton signed a 6-year, $50 million contract, which takes him through his arbitration years and also buys a couple free agent years too.

To estimate his trade value, I'm going to keep it very simple and not nearly as accurate as it could be. I'm looking at Upton's WAR (fWAR, rWAR, WARP) and am going to estimate what he'll be worth over the remaining years of his contract. This isn't going to produce a very accurate projection, but it's probably not too far off either. It's good enough for our puproses. If trading for Upton seems more a possibility than a dream, I'll look into deeper, but for now this will do.

I'm going to consider the last 4 and create a weighted average. Beginning in 2009 I get the following average WAR for Upton: 4.4, 2.1, 5.5 and 2.4. Weighting the seasons 2, 3, 4, and 5 results in an weighted average of 3.5.

Upton just completed his age 24 season so we should expect he'll get better over the next couple of years. We'll go with 4.0 WAR in 2013, 4.5 WAR in 2014 and 2015. That's a total of 13 WAR before his contract expires after the 2015 season.

If we use win values of $5.25 million, $5.5 million and $5.75 million we get a total value over those 3 years of $71.5 million. He'll earn $38.25 million meaning he has a surplus trade value of $33.25 million. In terms of prospects, that's worth approximately 1 top 10 hitting prospect or a couple top 10 pitching prospects.

The Cubs don't have a top 10 prospect, but Javier Baez won't be far off. He'll probably be in the 11-25 range, which is worth about $25.1 million.

I know GW mentioned a trade built around Garza and Castro, but if you could get Upton for Baez plus another prospect, would you do it? What about Garza and Baez?