With a little more than 48 hours until the non-waiver trade deadline, the Mets could still stand to add some offense. New Mets Juan Uribe and Kelly Johnson have gotten off to hot starts, as has Michael Conforto, but counting on two journeyman infielders, a rookie, and a resurgent Kirk Nieuwenhuis for the last two months of the season seems risky. The Mets would probably be well served to look to the outfield market.
Here's a table of the projected offensive production the Mets' current outfield options in left and center for the rest of the season, via Fangraphs, with current wRC+ and rest-of-season numbers listed.
Lagares and Nieuwenhuis are effectively platoon outfielders at this point. Lagares hits left-handed pitchers 30 percent better than his average offensive output for his career, while Nieuwenhuis hits righties around ten percent better for his career. With those adjustments in mind, here are the most commonly rumored outfielders available on the trade market with a breakdown of each one.
Parra is having a career year this year, riding a sky high .368 BABIP and a career high .194 ISO to a 140 wRC+. His xBABIP is .344, lending some credence to his new offensive skill, but the projection systems are much more bearish on him, predicting a regression back to a slightly-above-average bat—a fair projection given his career statistics. It's worth noting that Parra has an extreme platoon split for his career, hitting right handed pitches around ten percent better than his total statistics.
On a purely offensive basis, Parra seems to be an obvious upgrade over Nieuwenhuis as the left handed half of a center field platoon. However, for his career, Parra is a far-below-average defender in center, and has been worse over the past two seasons.
Still, Parra has to be considered an upgrade over Nieuwenhuis, particularly if you think his increased offensive performance is more legitimate than the projection systems do. Whether Parra is worth the Brewers' asking price—they were reportedly asking for Casey Meisner before that deal fell through and Meisner was dealt for Tyler Clippard—is another issue, but the Mets should be at the very least investigating this option.
Venable is a very similar fit to Parra, that being a left-handed platoon center field option to replace Nieuwenhuis. However, his advantage against right-handed pitchers is only around five percent over his total performance. Venable has provided better defensive value in center than Parra over his career but has been below average by both DRS and UZR over the past two seasons. This likely makes him a slight step down from Nieuwenhuis on the defensive side of the ball. Given that the difference between Venable and Nieuwenhuis is projected to be pretty minimal, this isn't an option the Mets should give up trade resources for.
Gomez has definitely slipped this year, but the projection systems still see him as one of the better offensive center field options over the remainder of the season. There are some troubling signs with Gomez, however. His power and BABIP have declined for the third consecutive season, while his strikeouts are up a bit. His defensive value has also declined, though he remains a likely plus and, at worst, a league-average defender in center.
Despite these warning signs, Gomez likely represents the best outfield upgrade for the Mets. He replaces their weakest position offensively, still plays solid defense, and is controlled for 2016, after which he could net the Mets a draft pick. However, it's not clear how available Gomez really is. Recent reports suggest that the Brewers want to be blown away and will simply hold Gomez if they're not. If Gomez were hitting like he did in 2013, he's the kind of player the Mets should blow away a team for. He's not, though, and the aforementioned red flags have to be considered. If the Brewers' price remains astronomical, there are more cost-effective upgrades elsewhere.
The 27-year-old Upton has had a somewhat disappointing walk year in San Diego. After a hot start, Upton has cooled off to the lowest total offensive production since 2012. Most of the decline can be contributed to a .304 BABIP that is 26 points below his career .330 mark, but his xBABIP of .309 backs up his current mark. Upton is a rental and is a poor left fielder, but the upgrade over Michael Conforto for the next couple months is projected to be fairly significant. However, Upton is dealing with an oblique injury, and there's a significant risk of overpaying for name value here rather than actual production. If Upton is indeed healthy and the Padres move him at a reasonable rental cost, the Mets absolutely should be interested.
The Tigers are caught in a bit of a no man's land between buying and selling. If they do decide to sell, Cespedes should definitely be one of the the Mets top targets. His 123 wRC+ is the highest he's posted since his rookie season in 2012. While he's a free swinger, he offers the legitimate right-handed power the Met lineup is missing right now and also provides good defensive value in left field, though he profiles very poorly in center. Cespedes should also come cheaper in a trade because, unlike Upton, he cannot be made a qualifying offer. If the Tigers determine that they're not going to contend this season, they'd likely be happy with a mid-tier prospect since they cannot pick up a late-first-round pick in next year's draft if Cespedes leaves in free agency. Given the lower cost and significant upgrade Cespedes presents over Conforto, this appears to be a great fit.
Byrd had a great 2013 with the Mets and turned that into a two-year deal with the Phillies. He hasn't been much more than a league-average bat since then, however, and his defense has declined to the point where he's an extreme liability, even in left. While he probably could be had for a song, Byrd just adds another bit of 'meh' to the Mets' current outfield situation, which is precisely the reason the Mets should be shopping for help in the first place.
Bruce is one of the more interesting names to consider on the list simply because he's controlled at very reasonable prices until 2017. While this will likely make him more expensive to acquire, Bruce is a piece that can help not just this year but the next two years as well. He's rebounded very nicely from a brutal 2014, with a career high walk rate and the lowest strikeout rate he's had since 2009 and has rediscovered the near-elite power that made him one of the best offensive right fielders in baseball from 2010 to 2013.
There are two caveats to consider, however. First, Bruce is a left handed bat limited to a corner outfield spot, a piece that doesn't fit the Mets left leaning lineup very well at the moment. Second, adding Bruce would create a logjam that seems to block Conforto until the end of the 2017 season. The Mets could look to flip Bruce or Granderson after the season to solve this issue, but it's a problem that merits consideration.
Gonzalez will probably be the most polarizing name on this list. After starting off slow, Gonzalez has looked as good as ever since the start of June. His red-hot July has his total offensive numbers back around his career level, and it seems like the knee issues that plagues him for most of last season and the start of this one are behind him.
That being said, this recent stretch could just be a hot streak, in which case Gonzalez's contract is a hot mess. Owed $17 million in 2016 and $20 million in 2017, the injury-prone Gonzalez could very quickly become a liability for the Mets. His home/road splits also merit attention, as he has not been much more than a league-average hitter away from Coors Field.