It's hardly a stretch to say that a Pirates outfielder deserves to be voted on to the National League All-Star team this season. The bigger question is which one to pick when filling out an 2016 Esurance MLB All-Star Game ballot.
Center fielder Andrew McCutchen is by far the biggest name of the group, a former NL Most Valuable Player Award winner who has made it to the Midsummer Classic in five straight years, including starts in 2014 and '15. Yet it's left fielder Starling Marte and right fielder Gregory Polanco, both aiming for their first All-Star selections, who have put up the most eye-catching numbers.
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There is plenty of competition for starting spots for the 2016 All-Star Game presented by MasterCard on July 12 in San Diego. The Nationals' Bryce Harper is authoring a worthy follow-up to his NL MVP campaign, the Cubs' Dexter Fowler is off to a scorching start, and the Brewers' Ryan Braun, the Mets' Yoenis Cespedes, the Phillies' Odubel Herrera, the Cardinals' Stephen Piscotty and the Marlins' Christian Yelich are among the other NL outfielders putting together strong first halves.
Still, it's difficult to ignore Pittsburgh, even though McCutchen has yet to reach his usual level of performance. While Cutch remains productive, he has career lows in batting average (.248), on-base percentage (.337), and weighted runs created-plus (117), with his lowest slugging percentage (.467) since 2011.

Both FanGraphs.com and Baseball-Reference.com have McCutchen just shy of one Win Above Replacement (WAR). That's solid, but it also lags behind his outfield mates.
According to FanGraphs, Polanco sat third among NL outfielders with 1.9 WAR through Saturday, three spots ahead of Marte (1.6). Baseball-Reference had them flipped, with Marte fourth (1.9) and Polanco 10th (1.4). A few tenths of a win is too small a margin from which to draw any conclusions, especially at this point in the season, but there are some significant differences between Marte and Polanco.
Marte, 27, has the more impressive Major League track record, coming off three straight seasons of All-Star-caliber performance, if not recognition. Patience is not among his virtues (four walks, 36 strikeouts), but a .407 BABIP and seven hit-by-pitches have helped him hit .325 with a .369 OBP. Marte also has been a force on the bases, ranking near the top of the league with 12 steals in 15 tries and also sitting among the leaders in FanGraphs' baserunning runs metric.
For the 24-year-old Polanco, a former top prospect, this looks like a breakout season. He has easily the more impressive approach, raising his walk rate (13.7 percent) and lowering his strikeout rate (17 percent), and he has generated more power than Marte. Polanco leads the NL with 16 doubles and has 23 extra-base hits, sporting a .526 slugging percentage.
In terms of overall offensive production, Polanco holds a modest lead on Marte in wRC+, 145 to 132. But while Polanco is no slouch with the glove, Marte possesses the stronger credentials in that department.
Since 2013, Marte leads all left fielders in Defensive Runs Saved (DRS), with 62, and he is third in Ultimate Zone Rating (UZR), at 22.4. He won his first NL Gold Glove Award last season, recording an NL-best 16 outfield assists. There's no reason to think his skills have diminished, not with him making plays like the one last Friday in which he cut down the tying run at the plate with an on-target throw that Statcast™ measured at a sizzling 100.6 mph.

Factoring in defense and baserunning, one could argue for Marte as the best all-around Bucs outfielder, and therefore most deserving of an All-Star spot. At the same time, Polanco's bat has made a compelling case of its own and likely has more room to grow going forward.
Picking one over the other might be a matter of taste, but either would be a worthy representative of 2016's most productive outfield.