Howard Sinker passes along a comment from Seth Stohs, proprietor of SethSpeaks.net:
Has Carlos Gomez already helped the Twins to more wins than Johan would have been able to? I would argue that when Gomez is in the lineup, the Twins have done better and in several cases, he has had a very direct effect on the Twins wins.
Questions like this fall under the unofficial category of trips to the 'What-If Ball'; unsolvable hypothetical questions about what might have been if history had been different. They're fun questions, and can occasionally be illustrative questions as well, but it helps when the questioner actually goes all the way to the ball.
First, let's restate Seth's premise, paraphrasing Seth himself, to get a more complete picture of his hypothesis:
Had the Twins not traded Santana to the Mets, they would not have had Carlos Gomez to play center field and would instead have gone with Denard Span, a much less exciting player. In addition, the Twins would likely not have started the season with Nick Blackburn in the rotation, who has turned out to be arguably the Twins best starting pitcher thus far in 2008. If you undo the trade, and incorporate the other factors resulting from undoing the trade, the Twins don't look to be any better in the win column than they are now.
On the surface, that seems a fairly compelling argument. Looking a little more closely, however, shows that a few of the premises in this argument can be legitimately questioned.
First (and I won't take credit for this one, since a commenter on Howard's Strib blog noted it first), while it's true that Gomez has directly contributed to a number of Twins wins (Opening Night at the very minimum, plus some others depending on how you measure such things), it's also true that a regular player not only gets more opportunities to contribute to a win, but also gets more chances to contribute to a loss. While I'm not a fan of Win Probability Added as a measure of player value, I do think WPA has something to contribute to this specific argument -- has a player contributed more to winning than he has to losing over a given period of time? And Gomez's current WPA, according to fangraphs.com, is a -0.19; Gomez's errors, struggles at the plate, and other young player woes have basically combined to negate the good things he's done in Twins wins, resulting in an effective net balance in the negative (and a balance that's the second worst such balance among AL outfielders, behind only Emil Brown of the Athletics). It's impossible to say if Denard Span or Jason Pridie would have been as electric in Twins wins as Gomez has been this year, but it's reasonable to assume that neither Pridie nor Span would likely have been much worse overall.
Second, and I will take credit for this one, it's actually possible that Blackburn would still have started the season with the Twins in the rotation even if the Twins had held onto Santana; had the Twins actually signed Santana to an extension, guaranteeing that he wouldn't just leave as a free agent after 2008, it's very likely that the Twins would not have worried about signing Livan Hernandez to fill the top of the rotation slot -- though whether that would be because they didn't feel the need for another innings-eater or because they wouldn't have wanted to spend the extra cash after committing so much to Santana is debatable. If we assume that Santana thus would have started the games that Hernandez has actually started in 2008, it would be Santana, not Hernandez, who would be the beneficiary of the best run support in the AL, and it would be hard to imagine that Santana, given that kind of run support, would be anything but unbeaten at this point.
So the simpler premise, that Gomez has helped the Twins to the same won-loss record they'd have had if they'd retained Santana, doesn't look quite so defensible given these thoughts: Gomez hasn't contributed anything in a win-loss sense that any other outfielder in the AL couldn't have done, at least according to WPA, and Santana arguably would have won at least one if not both of the games Hernandez has been charged with losing in his ten starts thus far.
On the flip side of the coin, the larger issue likely stands: the Twins might well have been better off, but they wouldn't have been hugely better off -- they'd most likely be a game or two above their current record, if that much -- and given the size of Santana's contract, they'd likely be in a much less flexibie position to adapt to team needs to pick up necessary pieces to continue to contend while Santana remained a Twin.
Just because I disagree with Seth's specific premise here doesn't mean I think the trade won't end up working out long-term.