Houston general manager Jeff Luhnow has certainly taken notice of Martinez, who entered Monday hitting .333 (27-for-81) with six homers and 18 RBIs in 20 games in the Venezuelan Winter League. Martinez was slugging .630 with an on-base percentage of .402.
"J.D. Martinez has been crushing the ball down there," Luhnow said. "He's worked on his swing, and the results are pretty positive so far. We're pretty happy with what's happening down there."
Martinez is coming off his third Major League season in which he batted .250 (74-for-296) with seven homers and 36 RBIs while playing 86 games. He did not make the club out of Spring Training, but wound up on the Opening Day roster to replace the injured Fernando Martinez.
Still, the Astros last month took him off the 40-man roster to create some space to protect another player from next week's Rule 5 Draft. Luhnow said nothing really has changed for Martinez despite the roster move.
"He's coming to camp to hopefully win himself a job," Luhnow said. "That's what we expect. What he's doing this winter, he's making a statement. He's still young and has a lot of promise. We took him off the roster because we needed to create space, but he could very easily find himself back on the roster on Opening Day."
Meanwhile, left-handed pitcher Rudy Owens, acquired from the Pirates in the Wandy Rodriguez deal in 2012, is healthy and pitching well in the Dominican Winter League. He's 2-1 with a 3.44 ERA in seven starts for Gigantes del Cibao, allowing 28 hits in 36 2/3 innings. Owens missed nearly all of last season following surgery to repair a stress fracture in his left foot.
Slugging first-base prospect Jonathan Singleton is playing this winter in Puerto Rico, and was hitting .275 with five homers and eight RBIs in 20 games for Santurce. Singleton batted a combined .230 with 11 homers and 44 RBIs between three different Minor League stops last season.
The prospect missed the first 50 games of the 2013 season for a second failed drug test, but he is expected to come to spring camp competing for a starting spot at first base.
"Jonathan Singleton is having a good winter, and that's been good to see, considering his year was a little mixed," Luhnow said.
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.