WASHINGTON -- Hunter Greene, the No. 2 selection in the 2017 MLB Draft, won't pitch the rest of the season with Class A Advanced Dayton due to an ulnar collateral ligament sprain in his right elbow. Reds general manager Nick Krall said Greene will strengthen his elbow at the Reds' Spring Training facility in Goodyear, Ariz., and try to avoid Tommy John surgery.
Greene, MLB Pipeline's No. 2-ranked Reds prospect, felt discomfort while throwing a bullpen session earlier this week before a team doctor diagnosed his injury. Krall hopes the right-hander will be healthy for next season.
"The positive, if there is any such thing, is that if it happens now when he's 18, he'll still only be 19 and ready to go," Reds interim manager Jim Riggleman said. "You almost figure it's going to happen. It happens to so many of them that I'm not in the least bit surprised."

Michael Lorenzen and Anthony DeSclafani dealt with similar injuries as Greene in 2016 and '17, respectively, and recovered without surgery.
Nick Senzel, who's rated the top Reds prospect by MLB Pipeline, is also out for the rest of this season with a torn tendon in his right index finger.
Greene was 3-7 with a 4.48 ERA, 89 strikeouts and 23 walks in 18 starts with Dayton this season. The Stevenson Ranch, Calif., native threw 19 pitches over 100 mph in 1 1/3 innings during the All-Star Futures Game on July 15.
Mahle optioned after start
After another poor performance Thursday against the Nationals, Tyler Mahle was optioned to Louisville, cutting the Reds' rotation to five pitchers. Cincinnati recalled Jesus Reyes from Louisville to add an eighth bullpen arm.
Mahle allowed six runs over 1 2/3 innings Thursday, marking the third time in his past four starts the right-hander didn't pitch past the third inning. Mahle has allowed 20 earned runs in 10 2/3 innings over his past four starts. In six June starts, Mahle was 3-0 with a 2.18 ERA.
Riggleman said Mahle is working with his mechanics, and the 23-year-old will have more leeway to do so in Louisville. Riggleman believes Mahle's Minor League stint will be short.
The Reds had been using a six-man rotation since July 22.
"He's an outstanding young pitcher who hit a rut like many do," Riggleman said. "Even position players, guys will come up and they just struggle. They go back, and when they come back to the big leagues, they're fine. I think that's what we're going to find with Tyler."
Reyes hasn't pitched in the Major Leagues but will add bullpen depth after Keury Mella threw 4 1/3 innings Thursday, the longest outing for a Reds reliever this season. Reyes has recorded a 3.86 ERA with 57 strikeouts and 27 walks in 31 games between Louisville and Double-A Pensacola this season. Reyes spent a day with the Reds in May but didn't enter the game.
"I feel proud, and I feel happy the Reds gave me another opportunity to be here," Reyes said through a translator.
Schebler back with club but not activated
Scott Schebler's 20-day rehab limit ended Friday as he returned from his rehab assignment with Louisville. The 27-year-old will work on his throwing program in Cincinnati and possibly rehab again before returning to the Major Leagues.
Schebler landed on the disabled list July 18 with a sprained AC joint in his right shoulder.