PAWTUCKET — It is hard to judge what brings a bigger smile to Marcus McBeth’s face, when you ask him about the way he is pitching or about how much he enjoys playing the piano.

 Mention either subject and the Pawtucket Red Sox reliever lights up. He is happy to talk about both.

 Playing the piano is something McBeth has done all his life, but it is only a hobby. Pitching is something he’s done for only five years, but it is what he does for a living.

 His ability to pitch is making his outlook brighter than ever. McBeth is putting up some great numbers as a Pawtucket reliever. Working as the primary set-up man for all-star closer Fernando Cabrera, McBeth has appeared in 27 games. He has a 2-0 record with three saves, an earned run average of 1.86. The slim right-hander has allowed only 22 hits in 38.2 innings, with 13 walks and 40 strikeouts. He has allowed only four hits in his last 15 innings on the mound, stretched over 10 appearances.

 “I have a tremendous amount of confidence in Marcus McBeth,’’ Pawtucket manager Ron Johnson said Thursday night after McBeth pitched a scoreless eighth inning in a 4-3 victory over Scranton/Wilkes Barre. “That’s why he’s in the game in those situations.’’

 McBeth’s numbers are the type that would attract attention from any Major League team. But what makes his performance that much more impressive is that he was drafted by Oakland in 2001 out of the University of South Carolina as an outfielder. He hit .235 in his first three years as a pro. In 2004, while playing at Modesto in Single A, he tried to make a diving catch.

 It changed his life. He was stepped on by a teammate. The knuckle on his right index finger was shattered.

 “It makes it hard to hold the bat,’’ he said. “They told me they didn’t know if I’d be able to throw again. I had to go through a lot of therapy, an eight-month long process. I ended up coming out of it as a pitcher.’’

 Because he had a strong arm and had pitched some in high school, an Oakland coach suggested he try pitching. To this day, McBeth cannot straighten his right index finger. There are some things he cannot do because of the problem, but holding a baseball is not one of them. And, in a strange turn, the situation with the finger actually has helped him develop an outstanding change-up, which has become his best pitch.

 “It was just a freak thing that happened,’’ McBeth said of his injury. “But  I’ve gotten a lot of help along the way. It’s gotten me to where I am now.’’

 McBeth, who also was a place kicker on the South Carolina football team as a freshman, was traded to Cincinnati in 2007. He appeared in 23 games for the Reds and compiled a 3-2 record with a 5.95 ERA. He spent most of last season with Louisville before being claimed by Boston off waivers late in the season.

 This year, at age 28, he has blossomed. His numbers are comparable, in terms of hits to innings pitched and strikeout-walk ratio, to those posted by Clay Buchholz and Fernando Cabrera, the team’s two all stars.

 McBeth loves to talk about pitching and how he is still learning the trade. But he also loves to talk about playing the piano. On one of their recent road trips, the PawSox waited in a hotel lobby. The lobby had a piano. McBeth could not resist.

 “Every time I see a piano, I have to play,’’ he said. “I’ve been playing since I was four years old. It was something my mom did. I enjoyed watching her do it. We took lessons together for about eight years, until I was about 13. I still play some now in my spare time.’’

 At the hotel, McBeth got to show off.

 “I don’t know if anybody knew that I played,’’ he said. “I wasn’t trying to do it to show anybody anything. I just wanted to play … I didn’t think guys would be that interested in it. I sat down and played one of my favorite songs. Everybody kind of got quiet. Everybody was listening.

 “They clapped at the end. I had no idea everybody was paying attention,’’ McBeth related. “Music is universal. It’s something everybody likes. It was a treat for me. It felt good.’’

 There have been a lot of good feelings for McBeth this season, on the field and at the piano.