"I just throw," he said. "When it leaves my hand, I have no idea how fast it is going to go."
Of course, he soon gets an idea by the swings of overmatched hitters and the reaction of excited fans.
"It's legit," Generals pitching coach Lance Painter said of Capps' eye-popping radar readings. "He's sitting around 98 [mph] now and regularly reaching 100."
Jackson began the season with Stephen Pryor as the closer and Capps in a set-up role. But the third-round pick in the 2011 First-Year Player Draft took over ninth-inning duties and has thrived since Pryor was promoted to Triple-A and then to Seattle.
Capps didn't allow a run in May and had struck out 21 while walking two over 14 2/3 innings in his last 10 appearances. Overall, the 6-foot-5 right-hander is 2-2 with five saves and a 1.65 ERA in 19 games, striking out 36 and walking nine in 27 1/3 innings.
Capps, 21, came into the season as the Mariners' No. 8 prospect, with Pryor at No. 9. Pryor, 22, recently made his Major League debut -- hitting 100 mph -- and Capps may not be that far away from Seattle himself.
"But it's not just about how hard you can throw," cautioned Jackson manager Jim Pankovits.
Still, hitting 100 on the radar guns certainly generates attention -- especially if you don't have trouble putting the ball in the strike zone.
"I had one other pitcher [Dan Cortes] a few years ago who could hit 100," Painter said. "To have two in one season is definitely special."
Capps, a country boy from eastern North Carolina, was a catcher at North Lenoir High School and red-shirted his first year at nearby Mt. Olive College (Division II). But once he got to the mound, he immediately started turning heads.
Capps won his first 24 decisions, setting an NCAA record. His only college loss in two seasons came at the Division II College World Series.
After pitching briefly in the Cape Cod League, Capps signed with Seattle for $500,000 and made four starts for Clinton in the Class A Midwest League. But it's in the bullpen where he has found a home.
Capps' velocity has jumped about five miles per hour since Spring Training, and his radar readings are no longer a surprise.
"He doesn't have much pitching experience, but he throws strikes and keeps the ball down," Painter said. "He's been impressive. I don't think he knows yet how good he can be."
Jackson, which leads the North Division of the Southern League, is one of the most talent-laden teams in the Minors, with three players ranked high among MLB.com's Top 100 Prospects -- Danny Hultzen (13), Tiajuan Walker (15) and Nick Franklin (46).
The first to make it to the Majors, though, was Pryor.
"We saw him pitch on TV, and everybody was really excited," Capps said. "It makes you want to get up to Seattle yourself even more."
Knee sidelines Paxton: Jackson left-hander James Paxton was put on the disabled list with a sore right knee after having to leave a start against Montgomery in the third inning. No structural damage was found. Paxton walked five while allowing four runs and four hits in 2 2/3 innings as his record fell to 3-3 and his ERA rose to 3.00. Paxton is rated as Seattle's No. 4 prospect.
Thornburg stays perfect: Tyler Thornburg improved to 7-0, but the Huntsville right-hander had to make an unexpected exit in the sixth inning at Tennessee. He was ejected for his comments when manager Darnell Coles, who was also tossed, argued a runner's interference call on the Stars. Thornburg, Milwaukee's No. 4 prospect, allowed three runs in five innings, his ERA rising slightly to 2.52.
Suns lose top hitter: Jacksonville outfielder Jake Smolinski was put on the disabled list after suffering a concussion in a game with Mobile. He was batting .298 and near the top of the Southern League with a .412 on-base percentage. Smolinski crashed into the left-field fence and hit his head on an electronic sign.
Lookouts get even: Chattanooga won Birmingham's 17th annual Rickwood Classic, holding off a ninth-inning rally to beat the Barons, 7-6, and avenge a one-run loss a year ago. A walk-off homer in the 11th inning beat the Lookouts last season. This year's game drew a crowd of 7,180 at 102-year-old Rickwood Field. Former two-time National League MVP Dale Murphy threw out the first pitch.