On July 28, 2006, the Nationals acquired Martis from the San Francisco Giants for veteran lefty relieverMike Stanton.[3] He joined the Savannah Sand Gnats of the South Atlantic League on August 1. After going 1–1 with a 3.80 ERA in four starts at Savannah, Martis was promoted to the High-A Potomac Nationals. He pitched two games in Potomac, giving up 4 earned runs in 12 innings. He ended the season with one appearance for the Double-A Harrisburg Senators, allowing 7 runs in 5 innings.
In 2007, Martis pitched for Potomac the entire season. In 26 starts and one relief appearance, he logged a 4.23 ERA over 151 innings, striking out 108 batters while issuing 52 walks.
Martis started the 2008 in Harrisburg. After going 4–4 with a 3.98 ERA and a 1.35 WHIP in 14 starts, he was promoted on June 21 to Triple-AColumbus, where he went 1–2 with a 3.02 ERA in 7 starts, striking out 42 batters and walking 17. He was selected as a member of the World Team for the 2008 All-Star Futures Game at Yankee Stadium.
Martis was called up to the Nationals on September 2, with the intent of assigning him to the bullpen. However, an injury to starter Collin Balester opened a spot for Martis in the starting rotation. He made his major league debut September 4, 2008, against the Atlanta Braves. He gave up 2 runs in 5 innings, earning the loss. He struck out the first batter he faced, Gregor Blanco. Chipper Jones got the first hit off Martis. In his first plate appearance, he drew a walk from Braves rookie James Parr, who, like Martis, was also making his first major-league appearance. Martis struck out Parr in Parr's first at-bat earlier in the game.[4] Martis got his first major league win on September 23, 2008, against the Florida Marlins.[5]
On May 2, 2009, against the St. Louis Cardinals, Martis pitched his first career complete game,[6] which was the Nationals' first complete game since Pedro Astacio's in 2006 against the Atlanta Braves.
Martis was designated for assignment on January 24, 2011. He cleared waivers and was sent outright to Triple-A Syracuse on February 2. He elected free agency following the season on November 2.
Pittsburgh Pirates
On November 23, 2011, he signed a minor league contract with the Pittsburgh Pirates.[7]
Minnesota Twins
On June 27, 2012, Martis was traded to the Minnesota Twins in exchange for cash or a player to be named later.[8] He had his contract selected to the major league roster on September 9, 2013, In 9.2 innings he struck out 7, working to a 5.59 ERA. He was sent outright to Triple-A Rochester Red Wings on October 2. He elected free agency following the season on October 7.
On May 20, 2015, Martis signed with the Bridgeport Bluefish of the Atlantic League of Professional Baseball. He was released on June 1. He made 1 start suffering the loss going 0.2 innings giving up 7 hits 8 earned runs (108.00 ERA) with 2 walks and 1 strikeout.
Lincoln Saltdogs
On June 6, 2015, Martis signed with the Lincoln Saltdogs of the American Association of Professional Baseball. He became a free agent following the season. In 17 games (16 starts) he tossed 106 innings going 6-3 with a 3.74 ERA and 79 strikeouts also throwing 2 complete games and 1 shutout.
On February 15, 2016, Martis re-signed with the Saltdogs for the 2016 season. He became a free agent following the season. In 24 games (18 starts) he tossed 121.1 innings going 9-8 with a 3.34 ERA with 93 strikeouts and throwing 1 complete game shutout.
Baltimore Orioles
On April 6, 2017, Martis signed a minor league contract with the Baltimore Orioles. He was released on July 24.
Lincoln Saltdogs (second stint)
On July 27, 2017, Martis re-signed with the Lincoln Saltdogs of the American Association. In 7 games (6 starts) he threw 40.1 innings going 4-1 with a 2.01 ERA and 32 strikeouts.
On February 17, 2018, Martis re-signed with the Saltdogs for the 2018 season. In 25 games (2 starts) he threw 41.1 innings going 3-5 with a 5.01 ERA and 32 strikeouts.
On February 14, 2019, Martis re-signed with the Saltdogs for the 2019 season. He was released on November 19. In 22 games (9 starts) he threw 65.2 innings struggling immensely going 2-7 with a 6.44 ERA with 38 strikeouts and 2 saves.
L&D Amsterdam
On February 23, 2020, Martis signed with L&D Amsterdam of the Honkbal Hoofdklasse for the 2020 season. In 11 games 13.2 innings of relief he went 1-0 with a 2.63 ERA with 16 strikeouts and 1 save.
On February 25, 2021, Martis re-signed with Amsterdam for the 2021 season. In 11 games (7 starts) he went 6-0 with a 0.91 ERA with 51 strikeouts throwing 1 complete game shutout and also picking up 1 save.
On February 11, 2022, Martis re-signed with Amsterdam for the 2022 season. He became a free agent following the season. In 17 games (8 starts) he went 6-1 with a 1.22 ERA with 72 strikeouts and 3 saves.
Curaçao Neptunus
On March 7, 2023, Martis signed with the Curaçao Neptunus of the Honkbal Hoofdklasse. In 17 starts 101.2 innings he went 8-3 with a 2.12 ERA with 88 strikeouts.
