So we have posts everywhere about the Garko trade, and I posted this comment in the original fanpost, but I think it's worthwhile enough to give it's own fanpost to.  Here's an evaluation of the trade:

I’ve taken the time to do some actual research, and come to a few conclusions. First, let’s assume Barnes is a grade C prospect. According to the work done here, that’s worth $2.1M to the Giants. If he was a grade B prospect he’d be worth $7.3M. So the question is, is Garko worth that to the Giants? Research done here also shows each additional WAR a hitter provides the Giants is actually worth more than 1 win, because of the low run scoring environment we play in.

Let’s call Garko a 2 WAR player, and say he’ll contribute .5 WAR to us the rest of this season. We should be on the hook for about $.2M for Garko this season. Using 40%, 60%, 80% arbitration numbers (I believe those are included in one of the articles I linked), we should pay Garko about $4M, $6M, $8M in each of the next 3 seasons, so we’re at about $18M or so. He accumulates 6.5 WAR over that time, worth about $29M. This is without even taking the low run scoring environment adjustment into account. Garko provides us with an approximate $11M in value, far more than Barnes, even as a Type B prospect, is worth. Great trade, we win.

If Garko is only a 1 WAR player, the numbers adjust (including how much he makes in arbitration) to $2M, $3M, $4M.  About $9.2M total for a 3.25 WAR (.25 for the this year's production) player, which is about $14.6M in value.  $5.4M in value from Garko, which doesn't quite offset a Type B prospect (though it'll be closer given the run scoring environment adjustment), but is worth more than a Type C prospect.  A pretty even trade at that point, given that Sickels had Barnes as a C+ prospect.

Credit goes to BtB for their research.