FRISCO -- The Rangers could benefit this season from the work Keone Kela, the powerful right-handed reliever, has done on his shoulder and his head in the last 10 months.

Kela underwent stem-cell therapy treatment in November to counter persistent shoulder soreness. He went on the disabled list twice last season because of the condition.

Well before that, Kela confronted the problems that caused the club to banish him to Triple-A Round Rock last April because of unprofessional conduct during the final stage of spring training. Kela learned from the experience.

"I had to keep the street away from the corporate, as simple as that," Kela said Saturday during a stop on the club's preseason caravan at the home of its Double-A affiliate.

The Rangers dearly missed Kela at the start of the season, just as they did during his two stays on the DL. Before Kela returned, the bullpen was 1-5 with a 6.27 ERA and one save in six chances. The Rangers were 4-8 in that stretch and never recovered.

The brief exile to the minors did accomplish what the club intended. Kela returned changed for the better.

"That's a certain condition that I am held responsible for," Kela said. "It's made me a better teammate, a better man.

"I know how to move around now. I have an understanding of what I need to do and how I need to be to help this team be the best they can be."

The next step is to stay on the field.

Kela has made fewer than 40 appearances in each of the last two seasons. He has been on the disabled list three times totaling 137 days in that span. The Rangers are a better club with a healthy Kela.

Kela tried stem-cell therapy to help the shoulder. Cells were removed from bone marrow in another part of the body and injected into the shoulder. Bone-marrow cells are used most often for cartilage, ligament and tendon repair.

The treatment is being used more often by pitchers, usually in hopes of avoiding major surgery. Bartolo Colon, in 2010, is the first pitcher known to have had the procedure. It helped Los Angeles Angels starter Garrett Richards avoid Tommy John surgery but did not have the same effect on teammate Andrew Heaney.

Kela said the treatment has helped. He has been throwing on flat ground from about 75 to 90 feet with no difficulty.

"I feel elastic," Kela said. "The body feels good. The arm feels good. I'm ready to go."

If the shoulder holds up, the Rangers have a better bullpen.

Kela averaged 11.87 strikeouts per nine innings last season, best ratio among club relievers with 20-plus innings. Having Kela and left-hander Jake Diekman, who averaged 10.97 whiffs per nine, for a full season makes this a better bullpen because of its enhanced strikeout capability. Diekman missed the first five months of last season while recovering from ulcerative colitis surgeries.

Kela also held opponents to a .135 batting average, second-best among major-league relievers with 20-plus innings. Opponents hit .277 against all other Rangers relievers.

"I have to be healthy," Kela said. "My rookie year was the most health I've had, and you saw what I did."

Kela made 68 appearances as a rookie in 2015 and had more strikeouts (68) and fewer hits allowed (52) than innings pitched (60 1/3). Do that again, and what was a bad bullpen last season takes a big step forward.

Twitter: @gfraley

Tough to hit

A look at the lowest batting average against among major league relievers with a minimum of 20 innings last season: