Okay, that title is a lie; there are probably a dozen or so players more underrated than the player I'm going to talk about. But I will still contend that Pat Burrell is very underappreciated. He is Philadelphia's version of A-Rod, albeit with less talent; he is the whipping boy for the franchise, all the fans hate him for some reason, and he's actually a good player.
What? Pat Burrell is a good player? How can that be? He's hitting just .207! He has "only" 10 homers and 34 RBI? How can you defend someone like that? Well, if you use numbers that more accurately measure a player's offensive ability, you'll find that his OBP is .371, and you'll find that RBI is a dumb statistic. Burrell's been hated and the fans have wanted him traded for years, but he's been a really good offensive player pretty much his entire career; fans just can't look past the low batting average numbers. Burrell's OPS+ this year is 101; 100 is league-average, so he's basically been an average hitter this year (by that metric). This has been a down year for him, too; his career OPS+ is 116, and he was at 124 and 125 in the last two years. He strikes out a lot, but does that really matter? Most of the time, it doesn't matter at all what kind of out you make; it's still an out, and those are bad. And Burrell has been good at not making those outs, as his OBP is .371. His slugging percentage is down this year, but most of that difference can be explained by his low BA (even for his standards), which is .207 right now.
Some critics like to say that Burrell's high OBP does not matter because they can't steal bases. This doesn't make sense; as long as he gets on base, it's possible for him to score, while if he does not get on base, he can't score, and he costs his team an out. For examples of people who think OBP is a bad stat for people with no speed, I'll refer you to Fire Joe Morgan's "clogging up the bases" category. The short answer is that these people are idiots. Getting on base = not making outs = helping your team score runs.
For the more nerdy fans, Burrell's EqA is currently .273, 14th among full-time left fielders in baseball. That says pretty much the same thing that the OPS+ statistic said; Burrell has been pretty much league-average this year. And he's been even better in the past. So, are the Phillies fans' expectations so high of Burrell that they expect him to be an All-Star caliber player, or are they just not looking at the whole pitcure? (Actually, this isn't just a rhetorical question; I do really want to know this. Why does Burrell get hated on so much? Is it as simple as his low BA and high K rate?)