(Matt Slocum/AP)

On May 24, Detwiler allowed five runs in the first inning while pitching for Syracuse at Rochester, the Twins AAA affiliate. “Nothing was really hit hard,” Detwiler said. “Everything was over the infield here. A little squibber to third base.” After the one-hour bus ride home, Knorr retreated to his office to write up his game report. He looked up and saw Detwiler.

“He kind of caught me off guard,” Knorr said today. “He was sitting in a chair across the desk. I looked up and saw him. I said, ‘What the [heck] do you want?’ ”

Detwiler wanted to talk. He told Knorr, “I feel like I’m making my pitches? What’s going on?”

Knorr had been waiting for Detwiler to ask. Knorr had a close relationship to Detwiler, whom he had managed for several years, starting at Class A Potomac in 2008, his first full professional season after the Nationals drafted him with the sixth pick in 2007. Knorr thought Detwiler had the ability to be a major leaguer, but he needed a different attitude. And he laid his opinion bare.

“I said, ‘Your attitude [stinks]. You go out there and if things don’t go right, you got that stupid smirk on your face, like you can’t believe you gave up a hit. And you give in,’ ” Knorr said. “I don’t like to use other players, but I said, ‘You watch David Price pitch, and if he gives up a hit, he wants the ball back like, that’s the last hit you’re going to get today. You don’t have that attitude.’ ”

The point Detwiler took from the talk was that he needed to pitch with more confidence and conviction. “He said, ‘It kind of looks like you didn’t have conviction. Everything’s fine. There’s just no conviction. That’s all that’s missing. It’s that extra little thing that’s going to tell everybody, this is my pitch, and it’s going to be better than you.’ ”

(Patrick Smith/GETTY IMAGES)

“It wasn’t really that I didn’t [care],” Detwiler said. “I kind of lacked confidence. A couple times I was out there, it wasn’t going my way, and I gave it the, ‘Here we go again.’ That’s actually what Knorr said. He’s like, you can’t say, ‘Here we go again.’ You gotta say, ‘[Forget] it. This is my game,’ and take it back.”

In nine major league starts this season, Detwiler has a 3.60 ERA. He’s allowed more than three runs in a start only once, against the Mets on Sept. 2, when he imploded for six runs in three innings. After that game, pitching coach Steve McCatty led him into the film room and showed him that every ball the Mets hit hard had been up in the strike zone.

Detwiler thrived Tuesday even without his best curveball, able to dominate the Phillies by simply throwing sinkers and changeups down in the strike zone, to both sides of the plate.

“The last two, I was just like, ‘I just got to keep the ball down,’ ” Detwiler said. “That’s what it boils down to. Pitch with conviction. Who cares if you get beat? And it’s kind of loosened me up a little bit to be myself instead of being so tight all the time and trying to make the perfect pitch.”

The attitude shift began in Knorr’s office back in Syracuse, and it was one Knorr had wanted to see him make for years.

“I always thought that about him,” Knorr said. “I was waiting for him to come in and ask me. If I go up and tell him, he’s not going to listen. If you wait for them to come up and ask you, they’re ready to listen.

“It’s something you can’t do overnight. Progressively, he got better and better. He had a better attitude. He’s shown that he’s improved. Next thing you know, he’s up here. He’s done great.”