Harrison, 27, broke on to the scene in 2014 as one of the game's best super utility guys, playing third base, left field, right field, second base, and shortstop last season. He expects to be the club's starting third baseman this season.
From 2011 to 2013, Harrison totaled 575 plate appearances, just less than the 550 plate appearances he got in 2014. He slashed just .250/.282/.367 with seven homers and 46 runs batted in over that time, with his OPS+ being just 80.
Some switch turned on for Harrison last year, hitting .315/.347/.490 with 13 homers and 52 runs batted in over the 575 plate appearances, including a 134 OPS+. Harrison was a member of the NL All-Star team and finished ninth in the MVP voting.
For third baseman between 3.000 and 3.999 years of MLB Service Time, Josh Harrison's new extension stacks up quite favorably, according to MLB Trade Rumors' Extension Tracker. Ryan Zimmerman's extension with the Nationals back in 2009 was the deal most similar to Harrison's in AAV. Zimmerman was guaranteed an average of $9 million per year for five seasons; Harrison was guaranteed an average of $9.1 million per year.
For the Pirates, Harrison's extension through 2019 adds another cornerstone player to be signed at least through 2017, with Andrew McCutchen, Starling Marte (who is signed through 2019), Francisco Liriano, Gerrit Cole (through 2019), and Gregory Polanco (through 2020) also being locked down in the longterm.