LAKE BUENA VISTA, Fla. -- Adam Conley could always throw hard. Doing it consistently has been the issue.

The 28-year-old left-hander took a major step forward in that department last season when he moved full time to the bullpen. In his late-inning relief role, Conley was able to let his fastball loose, and in the process, he witnessed the highest single-season jump in average fastball velocity of any pitcher in the Majors.

According to Statcast, Conley’s four-seam fastball velocity average in 2018 was 95.2 mph, a 5.5 mph increase from the 89.7 mph average he had in ‘17.

“The ‘pen certainly allows me to do it all the time,” Conley said. “If I’m going to throw 15 or 20 pitches, I can throw every one of them as hard as I can.”

Conley recorded a strikeout in a clean fifth inning in Sunday's 6-5 walk-off loss to the Braves at Champion Stadium. The lefty repeatedly touched 94 mph.

The easy explanation for the drastic jump in velocity is Conley being converted from a starter to a reliever. Because of the volume of innings starters throw, they aren’t always using max effort on every pitch.

In 2017, Conley made 22 starts and logged 102 2/3 innings, posting an 8-8 record with a 6.14 ERA.

Repeating his delivery was a problem, especially getting through the lineup a third time. So in 2018, the decision was made to convert Conley to the bullpen, where he became the club’s best lefty option, appearing in 52 games and logging 50 2/3 innings.

“We’d seen him at 94 [mph] a little bit, in that area,” Marlins manager Don Mattingly said, referring to Conley’s velocity prior to 2018. “And then he would lose velocity quickly during the course of a game. He’d go from 93-94 down to 88 and 87 within an inning or two. That was telling us something. Sometimes that tells you injury, or something happens. Or he needs to physically get stronger or whatever.”

Physically, Conley was fine. It was a matter of straightening out his delivery.

“I think with him, it was really clear,” Mattingly said. “It was a direct change last year when he changed mechanically to get his body in line, in position. All of a sudden, it was back to 96, 97 [mph], and it just stayed there.

“So really, for me, it was just mechanical. He wasn’t working against his body, he was working his body.”

Conley’s role this year is to face tough left-handed hitters in high-leverage situations. Because he has started and faced his share of right-handed hitters, he’s also capable of going more than one inning.

The Marlins don’t plan on having a true closer. They may go more with matchups, meaning Conley likely will get save chances depending on which opposing batters are lined up for the ninth inning.

Right-hander Drew Steckenrider is expected to get the most save chances, and veteran Sergio Romo is another option for the ninth.

Conley felt he was getting into a more consistent rhythm in 2017 after he was optioned to Triple-A New Orleans.

“In Triple-A, when I was struggling, before I came up, my velo wasn’t that high, but it was pretty high,” Conley said. “I was sitting 93 [mph], and I was still up to 96-97 as a starter.”

Listed at 6-foot-3, 200 pounds, Conley has always had many moving parts in his mechanics, so he has regularly tinkered to find a consistent arm slot.

“It’s always evolving for me,” Conley said. “But really, I’ve always tried to go really fast [tempo] and hit the ground really hard and have late shoulder rotation. Basically, create that coil effect on the mound.”

Per Statcast, 31 percent of Conley’s four-seam fastballs were 95 mph or higher. He reached 96 mph on 14.1 percent of his fastballs, and he touched 97 mph on 3.6 percent.

“My goal was always to do that, even three or four years ago; when you look at my velo and my stuff, I was trying to do that,” Conley said. “But the patterns my arms and legs were taking me and the path they were taking to get to certain places made me slow and kind of backed my release point up, stuff like that.”