These guys are flying under the radar or have been grossly underrated, but are quietly enjoying great seasons.
Ryan Ludwick (.264/.333/.555)
The 34 year-old journeyman outfielder has proven to be a nice free agent pickup for the Reds. He doesn't get the attention of teammates Joey Votto, Jay Bruce or Brandon Phillips, but the truth is that he's been the second best hitter on Cincinatti's NL Central leading club. The one-time All-Star's production fell off drastically after St. Louis dealt him on deadline day two years agao, but he looks rejuvenated back in the comforts of midwestern America. With 19 bombs in just 265 at-bats, his 13.9 AB/HR rate would rate second in the Senior Circuit (behind only Ryan Braun) if he had enough plate appearances to qualify. The .291 ISO is pretty good, too.
Matt Holliday (.322/.407/.557)
The six-time All-Star is consistently one of the best hitters in the game (I see him as a poor man's Miguel Cabrera), yet nobody ever talks about him. Since putting a putrid April slump behind him, all Holliday has done is bat .356/.444/.614 over the past three months. He's already matched last season's RBI total and is on track for his best all-around season since his heyday in Colorado. Doesn't need Albert Pujols.
Allen Craig (.295/.362/.556)
The Cardinals outfielder doesn't get much respect because of his inability to stay on the field. He had tough luck with injuries in the early-going, missing all of April and then two more weeks at the end of May, sitting out 41 games in all. Amazingly, all that time on the shelf hasn't affected his performance one bit. Just to give you an idea of how productive he's been on a per-game basis, if you project his numbers over 162 games he'd have 46 doubles, 38 home runs, 137 RBI, and 117 runs scored. And if that doesn't impress you, consider this; over his past 139 games (roughly a full season), he's batted .304/.362/.556 with 59 extra base hits and 94 RBI.
Paul Goldschmidt (.304/.372/.543)
Like Holliday, he's been much better since a sluggish start to the season. Going back to April 30th the talented sophomore has maintained .328/.394/.597 triple slash stats while blasting 14 of his 15 home runs. The brutal opening month has done irreparable damage to his counting stats, though his 30 doubles rank fifth in the Natioal League. His slugging percentage and OPS are both in the top 10, too. Even if he strikes out too much to keep hitting north of .300, Goldy has been the second best first-sacker in the NL this year behind Votto.
Jason Kubel (.287/.363/.557)
Is thriving in his Diamondbacks debut with a career best .270 ISO. His name is plastered all over the NL leaderboards, and his 72 ribbies are just four fewer than league leader Carlos Beltran's 76. The 26.3 percent whiff rate is alarming, but nobody's going to complain if he winds up with 30-plus dingers and 110 RBI. I see him finishing with numbers similar to Adam Lind's 2009 breakout.
Dexter Fowler (.294/.381/.508)
The major league leader in triples has finally started to realize his potential, and does a whole lot more than hit three-baggers. Colorado's speedster has already doubled his previous career high in round-trippers, stayed healthy and is much more efficient on the basepaths (nine of eleven in stolen base attempts). Could threaten the rare 20 doubles, 20 triples, 20 home run combo season last achieved by Curtis Granderson, I believe, but probably will have to settle for 15/15/15.
Adam LaRoche (.270/.345/.507)
Bryce Harper hogs all the media coverage, Ian Desmond is a revelation and Ryan Zimmerman has taken his game to another level since receiving a cortisone shots six weeks ago, but LaRoche is the one leading the Nats in home runs, RBI, OBP, SLG, OPS, and OPS+. It also helps that he's managed to avoid the injury bug that's feasted on Desmond, Zimmerman, Michael Morse, and Jayson Werth. With so many key pieces missing large chunks of time, he picked a good year to avoid a Mark Teixeira-esque slow start. Don't be surprised if the second half stud blows by the 30 homer/100 RBI benchmarks.
Carlos Quentin (.261/.380/.489)
It's not easy to get a lot of love when you suit up for the Padres, in my opinion the most boring team year-in and year-out. But even as he wastes away for a team well out of his contention, he continues to provide strong offensive numbers. With his .228 ISO Quentin has proved that he can still mash even after swapping home fields on opposite ends of the spectrum; the homer friendly U.S. Cellular Field for the spacious Petco. Missed all of April and most of May (not surprising for someone who averaged 120 games played from 2008-'11), but extrapolate his numbers over the course of a full season and he smashes 33 doubles and 30 home runs. His 143 OPS+ shines, but I'm more impressed by his 26/24 K/BB ratio.
Martin Prado (.300/.359/.424)
Another fine season from Prado, who's proving that his down 2011 was an aberration. He's nearly tripled his previous career high in thefts with 13 (against just one caught-stealing), has maintained a 46/40 K/BB rate and is gunning for his fourth .300 season in the past five years. As a leftfielder, the five home runs and .424 SLG leave a lot to be desired but he does have 28 doubles. There's no doubt his numbers would look even more impressive if he was still playing his natural position of second base, but that's just not possible with Dan Uggla around. I feel like many Braves are underrated this year--especially Jason Heyward, Freddie Freeman and Michael Bourn--because Chipper Jones' final season is overshadowing them.
Aaron Hill (.299/.355/.487)
You can argue Hill has been the best second baseman in the National League this year, better than Brandon Phillips, Jose Altuve and all the rest. Good to see Hill back on track after his career started to fizzle out in Toronto; since joining the Snakes late last year he's batting .303/.363/.483 with 59 extra base hits in 135 games.
Pirates not named Andrew McCutchen
Neil Walker, Pedro Alvarez and Garrett Jones have stepped up to provide the team's franchise player with some much needed support. All three have come to life at the plate after doing nothing in the season's first third. Walker and Jones are tied for the second best OPS+ on the Bucs with 122, while Alvarez is the only NL third baseman with a serious shot to rip 30 homers.