He feels the left-hander has the stuff to be a regular in the Major League rotation next season.
Rzepczynski spent much of this year at Triple-A Las Vegas, after opening the season on the disabled because of a broken finger suffered after being hit by a batted ball in Spring Training.
Now, Rzepczynski is getting the chance to show his stuff in the Blue Jays' rotation. And once again, he showed that inconsistency on Wednesday, allowing seven hits, three walks and three runs in five innings, as the Rangers defeated the Blue Jays, 8-1, before a crowd of 10,616 at Rogers Centre.
Jose Molina hit his fifth homer of the season to lead off the eighth against reliever Darren O'Day to put the Blue Jays on the board. It gave Toronto at least one home run in 10 consecutive games.
The Rangers got home runs by Ian Kinsler against Rzepczynski in the first and from Nelson Cruz against David Purcey in the ninth.
The loss ended the Blue Jays' seven-game winning streak against the Rangers, but for Rzepczynski, it was an all-too-familiar story of late.
"They're my nemesis," Rzepczynski said of the walks he continues to allow.
It isn't only the walks, but falling behind in the count also plagues Rzepczynski.
"He'll string together 15 or 20 good pitches, then all of a sudden he strings together 10 not-so-good pitches," Walton said. "We're working with the consistency, trying to stay away from the inconsistencies."
Because he used only 73 pitches last Saturday in a no-decision, Rzepczynski (1-4) was starting on three days' rest for the first time in his career. He made 79 pitches, 43 strikes, on Wednesday.
The idea was to get him out there again as soon as possible, so that he continues to work on being consistent.
"I felt fine," Rzepczynski said. "I felt really good. For the most part, my stuff was good, my stuff was there. I overthrew a couple of pitches. I get ahead, good. I fall behind, it turns out to be bad."
"You can't pitch behind, and that's what he's done probably the last three times out," manager Cito Gaston said. "He's going to have to improve that control or the same thing is going to keep happening to him. He got us through five innings, but it was not anything special. Pitching always set the tone, the kid over there threw pretty well."
Gaston referred to left-hander Derek Holland (3-3), who held the Blue Jays to three hits and two walks while striking out eight in five innings. The Blue Jays are 11-19 when the other team starts a left-hander.
"Holland went out there and kept them off the barrel, and the main thing, he kept them in the yard," Rangers manager Ron Washington said. "And the bullpen came in and did the rest."
Kinsler opened the game with his eighth homer of the season on a 3-1 pitch, then Rzepczynski walked the next batter, Michael Young. Vladimir Guerrero and Jeff Francoeur hit one-out singles to score another run. David Murphy grounded into a double play to end the inning.
"I tried to make some good pitches and fell behind," Rzepczynski said. "Kinsler was sitting on a fastball and he did the same thing to me last year in Texas."
Rzepczynski settled down in the second and set the Rangers down in order.
"When I get ahead, I get the ground ball and get out of it real quick, like the second inning," Rzepczynski said.
Young singled home the third run of the game in fifth after Kinsler singled, stole second and continued to third on catcher Jose Molina's throwing error.
Rzepczynski used his good sinker to induce his second double-play grounder of the game to limit the damage.
The Rangers scored an unearned run in the sixth against left-handed reliever Brian Tallet, after a throwing error by shortstop Yunel Escobar on a failed double-play attempt allowed Francoeur to score.
Bengie Molina's single against Josh Roenicke in the eighth scored Murphy, who had doubled.
Cruz homered in the ninth against Purcey after Young singled. Murphy singled with two out to score Guerrero, who had blooped a double.
"The main thing with those guys is keeping them in the ballpark," Washington said of the Blue Jays. "You keep them in the ballpark, you have a chance. If you let those guys get loose swinging with the bats and hitting them in the stands, you have no chance, because they don't always hit solos."
Meanwhile, Walton will continue to work with Rzepczynski to try to make him part of the starting rotation next year. There has been talk that he might become a reliever if he breaks with the big club next spring.
"I'd love to see him be a starting pitcher," Walton said. "That's my goal right now to turn him into a starting pitcher, because he has the ability to sink the ball, he has the ability to change the ball and he's got a great breaking ball. His breaking ball is one of the best in the Major Leagues from the left side.
"With that kind of breaking ball, he's always going to be able to be a reliever. In a worst-case scenario, he's going to be a good reliever. But right now, our focus is to turn him into a starting pitcher."
Larry Millson is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.