On September 10, 1985, Neil Walker was born in Pittsburgh. Nearly nineteen years later, the Pirates drafted Walker in the first round of Major League Baseball's 2004 amateur draft with the eleventh overall pick.
Pittsburgh's version of Joe Mauer, Walker grew up a Pirates fan and told his parents regularly that he wanted to play for the team. At Pine-Richalnd high school in Gibsonia, Pennsylvania, about a half-hour north of PNC Park, Walker played basketball, football, and baseball. He was recruited by colleges to play baseball or football, but the Pirates signed him after taking him in the first round of that draft. Walker's father Tom—who had also been a first-round pick and nearly joined Roberto Clemente on a relief flight for earthquake victims in Nicaragua in 1973, which crashed and took his life—pitched in the big leagues between 1972 and 1977.
Walker started his professional career in the Gulf Coast League in 2004 and worked his way up the Pirates' minor league system. As his minor league career progressed, the Pirates moved him from catcher to third base, where he spent a lot of time playing before they moved him again, this time to second base to accommodate Pedro Alvarez, who they had drafted with the second overall pick in the draft in 2008. In total, he spent much more time playing third than second in the minors.
And although the switch-hitter never put up outstanding numbers as a hitter in the first few years of his career, he made Baseball America's list of baseball's top one-hundred prospects from 2005 through 2008. He made his big league debut in 2009, though he only appeared in 17 games for the Pirates and hit poorly in the process.
The following year, however, Walker spent most of the season with the Pirates, and things went well. He hit .296/.349/.462 with 12 home runs and a 121 wRC+. At the time, Walker and then-Athletics pitcher Tyson Ross were featured in a story in the Wall Street Journal because they were the only two major league players who still lived at home with their parents.
Since that season, Walker has hit better than league average in every season of his major league career—and moved into his own place. His 2014 season—.271/.342/.467 with 23 home runs and a 131 wRC+ with 3.7 fWAR—was his beset at the plate, but even his worst years have been good. In total, Walker is a career .272/.338/.431 hitter with a 114 wRC+. He has struck out in 17.3 percent of his plate appearances and walked in 8.1 percent of them, both rates a bit higher than Daniel Murphy's career numbers.
On paper, it doesn't look like Walker's defense at second base is going to be spectacular, but as pointed out over at Fangraphs, Walker isn't all that different a player from Ben Zobrist as a hitter and a second baseman. Walker has played just a handful of games at third base in his major league career and played the rest of them at second.
If there's a concern with Walker's performance, it is his performance as a right-handed hitter against left-handed pitchers. He struggled mightily from that side of the plate in 2015, though his career numbers in those situations are much better. But his career splits—123 wRC+ vs. right-handed pitchers, 83 wRC+ against left-handed pitchers—are still fairly significant.
If a hitter is going to have splits, though, it's better that he do well against right-handed pitchers, as they make up the grand majority of the pitchers in the game. And the Mets are not lacking right-handed infielders on their roster, which, at least for now, includes Wilmer Flores and Ruben Tejada with Dilson Herrera not too far from ready in the minors.
Set to earn about $10.7 million in his last year of arbitration in 2016, Walker will be eligible for free agency at the end of the season. Right now, it seems fairly obvious that the Mets will give him a qualifying offer after the season. If he plays as well as he has thus far in his major league career, he will probably decline it. And if the team deems Dilson Herrera ready for the starting gig in 2017 and Walker signs elsewhere, the Mets will gain a first-round pick in that year's amateur draft.