"There wasn't much there that I didn't like," he said following Monday's 4-1 victory over the Toronto Blue Jays.
There isn't room for much disagreement there.
In what was Duke's fourth start of the spring, the young lefty was nearly flawless, allowing just three baserunners in five innings. And his efficiency -- which was not one of Duke's strongest suits last year -- left an impression.
"He looks like he knows what to do now," said Ronny Paulino, who was behind the plate for Duke's start on Monday. "He's grown up. He said that his fastball is getting more life, and I think that's making him look more mature."
That confidence was evident in the way Duke attacked hitters on Monday, mixing his changeup, fastball and sinker with ease. Duke needed just 51 pitches to complete his five innings of work and finished the game having faced the minimum number of Toronto hitters.
"I thought he looked great," manager John Russell said. "He has a great outlook, a fresh outlook here."
Monday's impressive outing was the latest in what has been three straight encouraging performances for the 24-year-old left-hander. Coming off a year in which he was plagued by injuries and control issues, Duke has now allowed just two runs and nine hits in his last three outings. He has pitched a combined 12 innings in those three games.
"Everything is right in line to where I want it to be," Duke said. "I don't think this is any different than the direction that I've been going in for a while now. I like where I'm going. I feel real good."
If the rotation weren't set in stone already, Duke might have secured his spot after Monday's performance. He has given management no reason to consider removing him for the starting staff, as he continues to look reminiscent of the Duke who was so successful as a rookie in 2005.
"I feel like I'm very close," said Duke, who went 8-2 with a 1.81 ERA that season. "I believe it's somewhere in me. I'm not there yet, but I'm definitely a lot closer than I have been in the last couple of years."
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.