So: Nate McLouth.
Ask Pirates and Braves fans about him and you'll get an assortment of curses. Those might be well deserved. As a Pirate, he hit .256/.334/.451 (.785 OPS) over 6 total years and 1741 PA, which is respectable enough. As a Brave, he hit a mere .229/.335/.364 (.699 OPS) over 3 years and 1005 PA, which is less so. Of course, the major problem that Pirates fans have with him is that when Pittsburgh brought him back to begin 2012, after a disappointing .677 OPS season with Atlanta in 2011, his line through 62 PA was .140/.210/.175 (.385 OPS), and the Pirates pretty much decided they'd had their fill of that by the end of the first month of the season. He was designated for assignment, bounced around the minors a bit, and found his way to the Baltimore Orioles. And that, in a nutshell, is why Braves and Pirates fans don't particularly care for him.
Because here is Nathan Richard McLouth's line as an Oriole going into Thursday's action: .285/.369/.450 (.819 OPS). That means the man the Pirates cut in April of 2012 for being an embarrassment to, well, the Pirates, has been the sixth-best left-fielder in baseball by OPS since the beginning of the 2012 season. And Pittsburgh and Atlanta fans would like an explanation, if at all possible.