Vasquez, who Minnesota picked up on waivers in November, was recently converted from a reliever to a starter, and he'll get his first Major League start in his Twins debut on Sunday.
"We saw him in Spring Training," Twins manager Ron Gardenhire said. "[He has a] live fastball. The ball jumps out of his hand. The breaking ball is OK, average.
"We haven't seen him as a starter, though. We were using him out of the bullpen [in Spring Training]. But he stretched out and stepped up, and he threw the ball great as a starter down there. So that's kind of exciting, because we kind of viewed him as a reliever out of Spring Training."
Vasquez pitched the previous eight seasons in the Arizona organization, making 141 appearances with the D-backs over the past three years. He's 5-10 and posted a 4.66 ERA in his big league career, allowing 71 earned runs in 137 innings.
Vasquez was primarily a reliever this season with Triple-A Rochester, as well, but he did start eight games. In a total of 31 appearances with the Red Wings, he went 9-6 with a 2.78 ERA, striking out 98 batters in 100 1/3 innings.
"We watched him and looked at him, and I think [Rochester pitching coach] Bobby [Cuellar] recommended, 'This guy's got enough pitches to start,'" Twins executive VP and general manager Terry Ryan said. "And with our need up here, that's why we made that decision. The other thing [is] ... [Vasquez] had a little trouble pitching back-to-back. So we decided, 'OK, if that's the case, let's start him and give him four days in between.' It was a combination [of factors]."
"We're excited to see him," Gardenhire said. "I'm anxious to see how his breaking ball is. I've only watched him on TV, and TV throws a little deception at you as far as how they're breaking and what kind of snap it has on it. I'm anxious to see him get out on the mound. It'll be kind of fun."
Walters returns after a lengthy stay on the DL. He was placed on the 15-day disabled list with right shoulder inflammation on June 14 and transferred to the 60-day DL on July 28. He's made eight rehab starts this season with Rochester, going 3-3 with a 4.01 ERA.
Walters has made seven starts with the Twins this season, going 2-2 with a 5.40 ERA.