I'm going to try a different path when answering this question than last time. Last time, I tried to address the question of whether or not Nyjer Morgan is, or could be, a good offensive player. There's no need to address that question any more. He's not. He's got a .341 OBP, a sub .700 OPS, and he's only stealing bases at a 68% clip. His walks are up a bit this year, but his batting average is down and in general, his line is pretty much in accord with what was generally expected of him coming in to 2009. His VORP is 1.7, barely above replacement level.
Morgan has, however, created an interesting argument for himself with his defense this year. Using FanGraphs' UZR, he's saved the most runs of any defender this year and he's got one of the highest UZR/150 rates of anyone in either league. He's on pace to save the Pirates somewhere in the vicinity of 25 runs in the outfield this year. A half of a season or so probably isn't enough data to draw any strong conclusions from UZR, but since Morgan's numbers are pretty similar to the ones he put up in almost 60 games last year, it's probably safe to say that Morgan is a plus-plus defender in the outfield.
The creates an interesting test for defensive metrics as the latest fad in baseball. Teams have gone with defense over offense before, but almost always in positions further to the right on the defensive spectrum; shortstop, center field, second base are the positions that most commonly give up offense for defense. To do it in left field seems to be a little crazy; Baseball Prospectus counts Morgan as about a win and a half above replacement right now using WARP, which measures defense with Fielding Runs Above Replacement (measured differently than UZR). That makes him the 100th best position player in baseball right now, out of 308 that have at least 100 PAs. That's really not good enough; you'll find a lot of corner fielders much closer to the top of the league than that (Jason Bay, Ryan Braun, Carl Crawford are all left fielders in the top 30, along with other corner outfielders like Nelson Cruz, Alex Rios, Shin-Soo Choo, Raul Ibanez, and Ichiro).
What this does is create an interesting puzzle for Huntington. Morgan's defense makes him more valuable than your typical speedy, light-hitting outfielder (Willy Taveras, Juan Pierre in most years when he doesn't hit that well), but it's still not really good enough to justify playing him in a corner position. If the Pirates do, in fact, choose to leave him there long-term (which doesn't seem likely to me, but they do seem to love a good defensive outfielder in left field and if Morgan doesn't play there, we may revisit this entire scenario with Gorkys Hernandez in two or three years' time), they're going to have to find offense from another spot on the diamond at the point in the future that they're nearing contention. Does that mean sacrificing defense at a position (shortstop, second base) that might be as important or more important to the pitchers? How does the big left field change the defensive spectrum at PNC Park?
Maybe a more pertinent question is how much offense a team with good defense and pitching needs. The Rays got a lot of attention last year for those two qualities, but they still scored 774 runs, just about dead average in the American League. Any team that starts Nyjer Morgan in left field isn't going to be average offensively, and that's a problem no matter how much defense he brings.