ALLENTOWN — A man wearing a fedora entered double-A Reading's clubhouse last month, and a weeknight minor-league baseball game suddenly carried some extra significance.

Gabe Kapler, on an off day as Phillies manager, greeted the Reading players in the clubhouse before taking a seat in the lower level to get a look at one of the organization's most promising arms. He was in Berks County on a busman's holiday to see a pitcher who could soon be joining his bullpen.

"That was a pretty cool surprise," said Seranthony Dominguez, who retired the three batters he faced that night in front of Kapler. "I just went out there and did my job."

Dominguez was promoted to triple A just four days later. That, he said, was also a surprise. The 23-year-old is proving to be a quick mover after he transitioned this winter to a relief role. He has the weapons — a fastball that touches 98 mph and a wipeout slider — to be a shutdown reliever. And perhaps a closer. It is that promise that caused Kapler to drive 70 miles.

Dominguez struck out 21 in 16 innings at double A and retired nine of the first 10 batters he faced in triple A. The Phillies, who signed Dominguez seven years ago when he was a Dominican teenager, moved the righthander to the bullpen this winter. He missed time last season with bicep tendinitis, and the team had a surplus of starters at double A. Moving Dominguez to the bullpen, where his pitches seem to flourish, was an easy decision.

"The challenge every day is just to be ready every day to pitch," Dominguez said. "But it feels the same."

Dominguez entered Tuesday night's game against Syracuse for his first real test at triple A. It was the seventh inning of a one-run game. His first triple-A appearance had come in middle relief. This had a bit more leverage.

His first pitch was a 96-mph fastball. Jacob Wilson guessed right and tried to pounce on it, but popped up. Tuffy Gosewisch, a former Phillies minor-leaguer, battled Dominguez to a full count before he slapped the pitcher's slider, which dives sharply as it reaches home, for a fly out to center. Michael Almanzar grounded out to third. Dominguez needed just 10 pitches to retire three batters.

It was a perfect triple-A test. All three batters were at least four years older than Dominguez and had plenty of triple-A experience. It was a step up from double A, and Dominguez passed with ease. The righthander looks the part.

"The most impressive thing is that he works at the bottom of the strike zone, which is very impressive," triple-A manager Gary Jones said. "The bottom line is going out and performing. There's been guys that have been hyped up but didn't perform. I just look at how a guy goes out on a daily basis and competes and performs."

The Phillies bullpen has been solid through the season's first month. Tommy Hunter has pitched well since returning from the disabled list. Yacksel Rios has been promising. Edubray Ramos, Hector Neris, and Luis Garcia are pitching like they did last season. Adam Morgan is continuing to have success. Pat Neshek and Mark Leiter Jr. will make their season debuts this month. There is no obvious space yet for Dominguez. But there is always room for a pitcher with a fastball that nears triple digits. And it seems to be just a matter of time until Kapler is watching him pitch again.

"This is what I've been working for," Dominguez said. "To get to the big leagues. And I'm extremely happy to move to the next step and be closer to the big leagues."