The Mets wound up with a decent outfield in 2013 thanks to the unexpected excellent season they got out of Marlon Byrd, but there's no doubt they still need outfielders. If the team goes into the season with a starting outfield of Eric Young Jr., Juan Lagares, and another internal option, something will have gone wrong this winter.
Jacoby Ellsbury figures to be the most sought-after outfielder on the free agent market. He was drafted and developed by the Red Sox and has spent his entire big league career with the team. In total, he's hit .297/.350/.439, good for a 109 wRC+, and he's stolen 241 bases at a success rate of 84 percent. He's also rated well defensively in center field. There have been a couple of downsides to Ellsbury's career, though.
Single seasons are arbitrary endpoints, but Ellsbury has not strung together back-to-back great seasons thus far in his career. His 9.1 fWAR in 2011 looks like an outlier, particularly since he hit 32 home runs that year and has never hit as many as 10 in any other single season. And Ellsbury hasn't been the perfect model of baseball health, missing significant chunks of the 2010 and 2012 seasons.
Ellsbury will likely get a long-term deal with a high average annual salary, and the Red Sox gave him a qualifying offer. If he leaves for another team, that team will have to shell out a lot of money and give up its highest available draft pick. The pick isn't a huge issue for the Mets this year, but Ellsbury recently turned thirty.
The season Juan Lagares had this year should not prevent the Mets from acquiring an elite center fielder, but Ellsbury just doesn't seem like a fit. Given his age, Sandy Alderson figures to be incredibly unlikely to give Ellsbury the long-term deal he'll most likely receive. The most likely scenario probably finds Ellsbury back in Boston next spring and for the foreseeable future.