Thanks to David Todd for putting up a post on the Justin Morneau trade this afternoon.
Judging from responses to the trade on Twitter, many fans think this is a major trade. It isn't. This has been Morneau's best season since 2010, but he's been about a replacement-level player since then. He isn't particularly good in the field or on the bases, and he only plays one position, so he has no real tactical value. That matters less as we head into September and rosters expand, but it's worth thinking about as the Pirates plan for the playoffs -- they'll almost certainly have both Morneau and Gaby Sanchez on their playoff roster, which means two roster spots for guys who play first base exclusively. And for all those tactical drawbacks, Morneau really doesn't hit all that well. He should get a bit of a bump heading into a situation with the Pirates where he'll be platooned, but he's nowhere near the hitter he used to be.
With all that said, if you're going to acquire Justin Morneau, this is the way to do it. The Pirates are only giving up Alex Presley and either a PTBNL or cash. After the Marlon Byrd trade, I gave my spiel about how players to be named rarely turn out to be anyone important, and then the Pirates ended up dealing Vic Black, one of their more interesting young bullpen arms. Well, this PTBNL isn't going to be anyone important, and the key clue is that the Twins have the option of taking cash instead. I'd expect this to be a random Class A arm, and nothing better than that. (UPDATE: Huntington says the PTBNL is "significant," so ... oh well.)
As for Presley, I suppose there's some chance of him having a late-career peak and being a good third outfielder in Minnesota, but given his pedigree and his tendency to pound the ball into the ground, I wouldn't count on it. And the Pirates, who are taking themselves seriously now, don't really have to bother with an undersized, underwhelming 28-year-old outfielder if there's no reasonable expectation that he'll develop into a solid regular in the future.
In other words, the Pirates aren't parting ways with anyone who's likely to bite them. Justin Morneau is a very marginal upgrade, and that's mostly because he allows the Pirates to use Garrett Jones or Jose Tabata to improve their pinch-hitting options. This is very different from the Marlon Byrd trade, which was a serious improvement. But if the Pirates are only going to give up Alex Presley and a random minor-leaguer for Morneau, then this is fine. And who knows -- maybe Morneau will catch fire in the last few weeks and become the real upgrade that a lot of Pirates fans seem to believe him to be. With this low a price to acquire him, there's no harm in taking the chance.