Junior José Guerra Maurera (born January 16, 1985) is a Venezuelan professional baseball pitcher for the Tecolotes de los Dos Laredos of the Mexican League.

Guerra is notable for his development of a split-finger fastball, a pitch which he learned while playing in the Venezuelan Professional Baseball League and ultimately led to his 2015 rise to the MLB.

"[1] In October 2001, the Atlanta Braves signed the then 16 year old Guerra, as an international free agent out of Venezuela, to play as a catcher.

After being converted to a pitcher in 2006,[2] he was released by the Braves and signed with the New York Mets in 2008, where he gained traction but failed a PED test in 2009.

[9] Guerra played each winter from 2008 to 2015 with the Tiburones de La Guaira of the Venezuelan Professional Baseball League in order to stay on the radars of MLB scouts.

[10] He made his major league debut a few days later on June 12, and pitched in a total of three games with the White Sox.

On October 7, 2015, Guerra was claimed off waivers by the Milwaukee Brewers as the first roster move of general manager David Stearns.

His rookie season, at the age of 31, resulted in accolades including the BBWAA naming Guerra the Brewers' Most Valuable Pitcher of 2016.

[12] A shoulder injury kept Guerra out of play in August 2016 and forced him to skip winter league baseball in the 2016–17 offseason.

[19] Guerra avoided the major injury problems that plagued him in prior seasons, appearing in a then-career best 31 games, but finished the 2018 campaign with a 6–9 record and a 4.09 ERA.