Bruce flew home to Texas to be with his wife, Hannah, to be present for the birth of their first child. The Bruces welcomed a boy, Carter, at 9:08 p.m., the Reds announced.
Cincinnati, whose bullpen has struggled and entered Monday with the second-most innings in the Majors, opted to add an eighth reliever instead of a position player.
"After the Cubs series -- I think they scored 38 runs or so in the four games -- that taxed our bullpen quite a bit," Reds manager Bryan Price said. "So bringing up Layne Somsen as an extra bullpen arm was definitely a need more so than an extra position player. We've got to just make sure our pitchers stay in the game so we don't have to burn a lot of those bench guys early in the ballgame."
Somsen had a 1.04 ERA over five appearances and 8 2/3 innings this season for Louisville. A 22nd-round pick in the 2013 Draft by the Reds out of South Dakota State University, the 26-year-old right-hander was the second-fastest player from the organization's 2013 Draft class to reach Triple-A -- after Lorenzen. Last season between Double-A Pensacola and Louisville, he had a 2.74 ERA in 62 1/3 innings across 27 games, with 47 hits allowed, 60 strikeouts, 30 walks and a 1.235 WHIP.
Somsen was in big league camp for the first time this year at Spring Training as a non-roster invite.
"When I went to camp, it was a good experience, but I wasn't throwing to the best of my ability," Somsen said. "When I went to Louisville, I wrinkled out some of the problems in my mechanics, and I feel like I'm back to where I was at the end of last year going into the Fall League. I'm feeling pretty good."
Somsen, who has a delivery that uncannily resembles that of former Giants All-Star Tim Lincecum, has a three-pitch repertoire, featuring a fastball, curveball and changeup.
"First of all, he's had some success at the higher levels of our system," Price said. "It lends itself to a young guy having some optimism and the expectation that he can pitch well at this level because he's pitched well at the higher levels of the Minor Leagues. … I think he showed us in Spring Training just some competitiveness that you really need to be able to bridge that gap."
When Somsen was cut from the Spring Training roster last month, the Reds instructed him to sharpen his curveball so he would be better able to throw it for strikes.
"My breaking ball was kind of backing up on me," Somsen said. "I was getting too far over the top. You guys know I throw pretty high up top, but I was getting a little too far over. It was coming back at me rather than coming across to a right-handed hitter, like a 1-to-7 motion. That's what they wanted me to work on and what I've been able to figure out in Louisville."