Who's your most surprising National?

As Ian Desmond's 23rd homer of the season sailed over the fence last night at Citi Field, I thought to myself, "Self, there's no way you could've seen this coming." Desmond hit .253 with eight home runs and a .656 OPS last season. Anyone that says they expected the Nationals' shortstop to be batting .295 with 23 homers and a .854 OPS and to have a suddenly near-flawless glove this season is lying to themselves. Given what he's done this season, Desmond is a sure candidate for the most surprising performance turned in by a Nationals' player this season. But he's not the only guy who has put up surprisingly strong numbers. Take Adam LaRoche, who many fans were willing to kick to the curb this offseason. LaRoche has 29 home runs, 92 RBIs and one of the smoothest gloves at first base you'll find anywhere in the majors. We knew Gio Gonzalez was going to be good when he came aboard via a trade with the A's this offseason, but did we know he'd be this good? Gonzalez has a 19-7 record, 2.93 ERA and 191 strikeouts in 181 1/3 innings. Despite all his ups and downs, Bryce Harper has put together an incredibly impressive rookie season, one of the most impressive by a teenager in major league history. He's hitting .262 with 18 homers, 49 RBIs, 13 stolen bases and plus defense in center field. There's Jordan Zimmermann, who was leading the majors in ERA at one point a handful of weeks ago, and even with a bit of a rough stretch lately, he still has a lowly 3.01 ERA. Ross Detwiler appears to have figured out how to pitch at the major league level. He has an impressive 3.23 ERA and is one win away from double-digit wins for the season. Even with his broken wrist forcing him out of action for much of the season, Jayson Werth has done exceptional work when he's been in the lineup, batting .306 on the season, putting together a ridiculous .399 on-base percentage and stabilizing the leadoff spot. Guys like Tyler Moore (.279 and nine home runs in just 140 at-bats as a rookie) and Roger Bernadina (.300 and 15 stolen bases) have really impressed manager Davey Johnson and have been valuable members of this team even though they've become role players of late. Tyler Clippard has gotten thrust into the closer's role and has excelled, recording 31 saves in 35 chances. There are others, as well, like Craig Stammen, Danny Espinosa and rookie Christian Garcia who have turned in strong performances with the big league club. Any number of guys could be considered the most surprising story of the Nationals' 2012 season thus far. If you had to pick just one National who has surprised you the most this season, however, who would it be?