Montgomery needed only 70 pitches in six innings. He walked one, struck out two and allowed just one run.
The Yankees reportedly had toyed with the idea of finding another fifth starter. And if the rumors are correct, they were still looking until earlier this week before the Orioles signed Alex Cobb. Not anymore.
"I really like where he is," Boone said. "His secondary stuff is hard to hit. Guys don't see it well."
Montgomery had a strong rookie year in 2017, going 9-7 with a 3.88 ERA. He expects a better year in '18.
"My change is good," Montgomery said. "I feel I can throw anything in any count."
He said one thing he learned last year was that he can rely on his curveball.
"Even if they know it, I can throw it," Montgomery said.
Montgomery credits veteran starter CC Sabathia for his improvement.
"CC helps me every day," Montgomery said. "He's always pumping me up, telling me to be patient."
Asked what he thought Montgomery was capable of, Boone said: "I want him to give us a chance to win every time he goes out there. I know his goal is to go deep into games."
After Montgomery's six innings Thursday, Domingo German, who's vying for a bullpen spot, pitched the final three. A right-hander who consistenly threw his fastball at 95 mph Thursday, German was near spotless, facing 10 batters and allowing only one baserunner on an error.