Since coming into the league in 2005, no catcher apart from Joe Mauer has been as prodigious offensively as Atlanta Braves catcher Brian McCann. McCann has seven 20-homer seasons in that time span and six seasons with a wRC+ of 119 or better.
McCann's defense is rarely talked about, but Baseball Prospectus had him rated as one of the top five pitch-framers in baseball this season through August, saving 18.5 runs. In May, Baseball Prospectus noted that McCann had saved the Braves almost 125 runs over the past five seasons. The Braves' catcher has also held his own in terms of blocking pitches, rating 2.1 runs above average in 2013 and 3.2 runs above average in 2012 according to Fangraphs.
There are some concerns for McCann going forward, however. He turns 30 in February and catchers don't typically stay catchers through their mid-30s. McCann's bat also carries some red flags. In 2012 he had the worst year of his career, as he hit just .230/.300/.399 in 120 games while dealing with a nagging shoulder injury. McCann underwent shoulder surgery that offseason, which caused him to miss the first month of the 2013 season. He rebounded to hit .256/.336/.461, but one of the problems from 2012 didn't go away. For his career, McCann has a 99 wRC+ against left-handed pitching, but in 2012 and 2013 he slipped to 80 and 72 wRC+ against southpaws.
Despite his watchdog antics in 2013, McCann figures to make a lot of money this offseason. The Fangraphs community projected McCann to get four years and $59 million. That seems completely unrealistic given McCann's pedigree and the influx of TV money into many big market teams. One GM speculated ten days ago that McCann could get $100 million. At worst, McCann should get five years and $75 million, the same amount of money Yadier Molina received when he signed his extension with the Cardinals back in 2012. Given the lack of quality catchers in baseball, it really shouldn't surprise anyone if McCann gets upwards of 90 million over five or six years.
In terms of actual improvement of the team, McCann makes a lot of sense for the Mets, as he does for most teams in baseball. In terms of practicality and where the Mets will choose to invest their money, he's not a very good fit at all. Travis d'Arnaud hit just .202/.286/.263 in 112 at-bats in 2013, but he is only 24 and there's no chance the Mets will give up on one of the best catching prospects in baseball after a handful of plate appearances.
There's also the fact that the Mets do not have the luxury of burying a defensive liability at designated hitter, so when McCann inevitably moves away from catcher in a couple of years they would be forced to play him at first base. Finally, even if the Mets did not feel comfortable with d'Arnaud going forward, the organization has holes in the outfield and at shortstop that are much more glaring and it seems unlikely the Mets won't improve those positions first. Basically, the chances of Brian McCann wearing a Mets uniform in 2014 are halfway between zero and nothing.