As Talking Chop notes, today is the six-year anniversary of the Pirates' trade of Nate McLouth for Charlie Morton, Jeff Locke and Gorkys Hernandez. With Morton and Locke still in the Bucs' rotation, the trade is still bearing fruit for the Bucs. The quality of that fruit has been questionable at times, but the McLouth deal turned out to be one of the more successful of Neal Huntington's rebuilding trades.
McLouth didn't accomplish much in Atlanta, finishing his career there with just 0.1 fWAR. That was probably partially incidental -- McLouth returned to Pittsburgh in 2012 and flamed out there, too, but he had a strong comeback season with the Orioles in 2013, so it's easy to imagine that his seasons in Atlanta could have gone better. The trade looks like a case of Huntington unloading a player at exactly the right time, but it was partially good fortune that things worked out so smoothly for the Pirates. If Huntington really thought McLouth was washed up, he probably wouldn't signed him to a three-year extension only months before, and he probably wouldn't have signed him in 2012, either. The Bucs probably thought they were giving up a good player.
As good players go, though, McLouth was a square peg in Pittsburgh. The much-ballyhooed 2008 "Best Outfield in Baseball" of Jason Bay, McLouth and Xavier Nady was strong offensively, but its poor defense was one reason the Pirates' pitching staff looked so bad. (One reason among many, to be fair.) And the Bucs had an outstanding center field prospect in Andrew McCutchen ready for the big leagues. Bay and Nady were already gone by then, and the Pirates could have bumped McLouth to a corner. That wouldn't have been the worst thing in the world. But McLouth's bat profiled better in center field, and at 27, it appeared his value probably wouldn't get any higher. (As it turned out, he was teetering on the edge of a cliff, but Huntington probably didn't really know that.)
So the Bucs traded him to Atlanta for three mid-grade prospects. I didn't love the trade at the time (I called it "a bit of a grab bag"), but I understood it. (Amusingly, that post also describes Locke as a "hard-throwing lefty starter" -- if I recall correctly, much of what was online about him at the time described 94-MPH-type velocity, which was definitely hard-throwing for a lefty back then. Here's more of what I wrote about the trade at the time.) Most Pirates fans didn't like the deal at all, of course, and as Hernandez failed to develop and Morton took his time doing so, it took awhile for the trade to look much better, even as McLouth flamed out in Atlanta. It didn't help that the Pirates initially didn't seem to know what to do with Morton -- they at one point forbade him from throwing his two-seamer, which seems ludicrous now.
Gradually, though, Morton morphed into an inconsistent but mostly fairly effective ground-ball pitcher, and so far he's produced 6.4 fWAR for the Bucs. Locke headed to Class A+ Lynchburg after the trade and spent two more years in the minors before making it to the bigs, but he spent the 2013 and 2014 seasons as helpful rotation filler. His 2013 All-Star berth wasn't a good indication of his ability, but his poor results so far this season aren't either. He's still cost-controlled as well.
Even adjusting a bit for McLouth's unforeseeably steep decline, the trade was a clear win for the Bucs. They got two pitchers who have already been helpful for several seasons and could be helpful for several more. That's exactly what they were probably hoping to get -- a team needs superstars, but it needs decent regulars too, and getting superstars in trades is tough. Morton and Locke aren't outstanding, and they're occasionally frustrating, but they've been helpful and cheap, and McLouth didn't serve much of a purpose for a rebuilding team.