THURSDAY: The Rangers announced they've agreed to sign Harrison to a five-year extension that includes an option for 2018. The club will hold a press conference at Rangers Ballpark today to announce the deal.

WEDNESDAY: The Rangers have agreed to a five-year, $55MM extension with Matt Harrison after the left-hander passed a physical, Jeff Wilson of the Fort Worth Star-Telegram reports (Twitter links). The contract contains an team option for a sixth year in 2018 that can become a vesting option if Harrison reaches certain innings plateaus, Wilson adds. Harrison, 27, is represented by the ACES agency.

Harrison will receive a $1MM signing bonus and the rest of his contract breaks down as follows, according to Wilson. The southpaw will earn $5MM in 2013, $8MM in 2014 and then $13MM in each of the following three seasons. The 2018 option is worth $13.25MM (with a $2MM buyout) but could be worth as much as $15.75MM. That option will vest if Harrison pitches at least 200 innings in each of the 2015-17 seasons.

The two sides were known to be exploring a multiyear deal earlier this offseason. The deal covers Harrison's final two years of arbitration eligibility and his first three free agent years. I noted back in November that Chad Billingsley's three-year, $35MM extension with the Dodgers was a decent comparable for a possible Harrison extension and in fact this new contract will pay Harrison an average annual value of just under Billingsley's AAV.

This extension could end up being very team-friendly if Harrison continues his development as a front-of-the-rotation starter. Harrison has a 3.34 ERA with a 2.28 K/BB ratio and 5.8 K/9 rate over 399 innings in 2011-12 and showed a talent for keeping the ball on the ground at Rangers Ballpark, with a 49% groundball rate in 2012 and a 47.5% GBR in 2011.

Texas GM Jon Daniels has been quick to lock up key members of his roster, as Harrison joining Derek Holland, Elvis Andrus, Ian Kinsler, Nelson Cruz as Rangers who have signed extensions within the last 12 months. As Wilson points out, the Rangers now have four young starting pitchers (Harrison, Holland, Yu Darvish and Alexi Ogando, the oldest of the group at age 29) who are controlled through at least the 2016 season.