So now we have another big piece of the puzzle.

When the Diamondbacks traded Justin Upton to the Braves for Martín Prado and a squad of marginal prospects, there was something that just didn't add up: Upton was signed through 2015, Prado just 2013. Could it possibly make sense to trade three years of Upton for one year of Prado?

Well, Wednesday the Diamondbacks announced that they and Prado have agreed on a contract extension running through 2016; since the announcement, sources have reported the deal is worth $40 million.

Tuesday, Nick Piecoro wrote this about the general consensus about the trade: "My opinion on the deal is right in line with the general consensus: The Diamondbacks didn’t get enough."

More from Piecoro:

I think getting a contract extension done with Prado changes the deal somewhat, although maybe not as much as others (including apparently the Diamondbacks) might think.

Generally, if you’re trading an established star who has three years to go before free agency, you should probably get back potential star-quality young players who will be under club control (i.e., cheap) for at least as many years as the player you’re trading away. Yes, they got several young players back in the deal, but if the scouting community is to be believed, they don’t have near the ceiling that we’re talking about here. (And if you can’t get that kind of return, you might as well just keep Upton.)

--snip--

There seem to be a lot of folks using Prado’s WAR as a justification of the deal. He was worth 4.9 wins in 2010, 1.8 in 2011 and 5.4 in 2012, per Baseball Reference. That’s 12.1 wins over the past three seasons. Upton was worth 1.4, 5.7 and 2.1 in the same three years, a total of 9.2.

This does tell us something – it confirms Prado’s value – but it’s leaving out an important piece of information: Age. Prado posted those numbers in his ages 26-28 seasons. Upton did all that between ages 22-24. Upton still might be several years from his peak.

Absolutely true. Prado has probably peaked, while Upton probably has not.

I do think it's worth mentioning that Upton is not, over the next three years, particularly cheap. I mean, he might well be a bargain. But he's not some pre-arbitration kid who's going to earn practically nothing. Three years ago, Upton signed a six-year contract. Over these next three seasons, Upton will earn $38.5 million.

Leaving aside completely the minor leaguers in the trade, we might now ask this question: Would you rather have Justin Upton for the next three seasons at $38.5 million, or Martin Prado for the next four seasons at $40 million?

I mean, you have to love Upton's potential and Wins Above Replacement isn't everything, but I would have to think long and hard about that one. FanGraphs has Prado worth around $65 million over the last four seasons; considering both age-related decline and natural salary inflation, doesn't $40 million for the next four seasons seem like a pretty good deal? Meanwhile, FanGraphs has Upton worth $52 million over the last three seasons; at $38.5 over the next three, he also seems a pretty good deal.

Yes, it's all fine and dandy to talk about Upton's potential, but the fact is that he's been an outstanding player in one of the last three seasons. I expect him to become a consistently outstanding player, but that's far from a sure thing.

But with Prado locked up through 2016 and with the well for Upton perhaps poisoned in Phoenix and with the Diamondbacks getting a few prospects (however marginal) in the deal, I'm less inclined to think this was a big mistake than I did last week.

Now, about the Trevor Bauer deal ...

Update: As someone pointed out in the comments, Randall Delgado is more than a "marginal prospect". If he pitches well for the Diamondbacks, they could easily "win" this trade.