Singleton, who was suspended Jan. 9, will be allowed to compete in spring games and could even get plugged into some Grapefruit League games.
"I think we've always thought this is the year Jonathan Singleton probably gets to the big leagues, whether it's the beginning, middle or end of the season," Luhnow said. "I think he's got a good shot. If he stays healthy and continues to produce, he'll be there."
Singleton will miss the first seven weeks of the season because of his second positive drug test, which means he'll lose about 200 at-bats that are crucial in his development. He hit .284 with 21 homers and 79 RBIs last year in 131 games at Double-A Corpus Christi.
"It's a setback because it's 50 games against high-caliber competition," Luhnow said. "He'll still be able to get swings, he'll still be able to participate in baseball activity down in extended [spring], but it's a little different facing pitchers and doing batting practice at extended than it is in [Triple-A] Oklahoma City and in Houston. It's a setback, no question about it, but hopefully it's also been a learning experience and something we can build on from here."