Photo: Karen Warren/Staff Photographer

WEST PALM BEACH, Fla. — For four months now, Forrest Whitley has warmed up with a softball, the latest on a lengthy list of tweaks for the Astros’ top pitching prospect who can’t discover continuity.

On the days he’s scheduled to pitch, Whitley tosses the 7-ounce ball approximately 10 times before finally picking up a baseball. Other established Astros pitchers practice the pre-outing routine. Whitley would have continued it Saturday in Jupiter. A problem arose — he neglected to pack the softballs.

On Texas Sports Nation: Justin Verlander leaves spring game with triceps soreness

Whitley nonetheless threw his one inning. His velocity was concerning and his arsenal forgettable. Just one of his four-seam fastballs was harder than 95 mph. One did not crack 90 mph. He fell behind 2-1 or worse on each of the four Cardinals he faced. Two struck out and another was hit by a pitch.

“I wasn’t necessarily trying to throw all that hard,” Whitley said Sunday, ascribing all of his struggles the previous day to a softball-less warmup. “There was a couple I tried to let go, but I wasn’t feeling the ball correctly in my hand. I was like, ‘If I let this ball go, it’s either going to go behind him or in the dirt. I just have to find the (strike) zone.’

“Unfortunately, it was a small sample size. I feel like if I had gone out for the second inning, I would have corrected those mistakes, but unfortunately I only got one.”

Whitley had reached his limit, a puzzling governor on what once was the game’s best pitching prospect. Whitley never was a candidate to make the team’s opening day roster, but his diminished workload has made him something of a forgotten man.

Fifteen games into Grapefruit League play, Whitley’s thrown 3 2/3 innings. Auditions for the Astros’ fifth starter spot, coupled with the need for established major league starters to build up, make innings already scarce. Pitching coach Brent Strom lamented there aren’t “enough innings to go around.”

Each of Whitley’s last two appearances were prescheduled, one-inning stints. In his last outing, he followed fellow Class AAA starting pitching prospect Brandon Bielak, whom the organization is treating like a normal starter.

“No, (I’m) not frustrated, just being patient with it,” Whitley said. “I’m not super eager to get out there and blow it out for five innings but just kind of enjoying the process day to day and not necessarily really looking forward to one particular moment, but just kind of looking forward to day to day work.”

On Texas Sports Nation: Brandon Bielak trying to make an impression in spring

Asked about his one-inning workload Saturday, Whitley raised an eyebrow. “I’ve asked the same question as you,” Whitley said, without realizing the limit was a consequence of his own change.

“Whitley was not ready to come into camp physically and compete for a position, for whatever reason, in my opinion,” Strom said. “So we had to slow-walk him a little bit.”

Whitley does not dispute Strom’s assertion, however alarming it may seem.

After an array of injuries interrupted each of his last two minor league seasons, Whitley altered his training regimen this winter. He relocated to Phoenix after spending his prior offseasons in Texas. He trained at the Fischer Institute.

Whitley worked out only four days per week, often taking Wednesdays off to golf. He ate more. He did not begin throwing until December. After reporting to spring training in 2018 at 190 pounds, he weighed 230 this year.

“Compared to last year, it was definitely less prepared,” Whitley said Sunday. “I wouldn’t say I was completely unprepared for camp, so to say. I was definitely less prepared than last season, for sure, and that was just because (of) a little bit of foresight for some longevity this season rather than coming to spring training where stats don’t count.

“Impressing people right now isn’t really what I’m trying to do. I’m just trying to get my work in, stay healthy and do everything I can to have a successful season.”

After he watched Whitley’s unimpressive first live batting practice session of spring, Strom stepped forward for more individualized instruction. Strom, bullpen coach Josh Miller and minor league pitching coordinator Bill Murphy gathered with the other pitching coaches in camp for a sit-down to solve Whitley’s problem.

“We went in and looked at what made him successful to get drafted,” Strom said. “We opted to roll the dice and go back to what got him drafted in the first place. That’s the delivery he’s using now, which is very similar to when he was a high school kid in San Antonio.”

Strom urged Whitley to do what felt “natural.” He implemented an arm swing he hadn’t used since high school. While in the windup, Whitley now brings his hands over his head, something he acknowledges, “I’ve never really done that in the past, but it just feels right.”

Strom said there’s now a “stab” in Whitley’s delivery — a small punch toward the ground before he lifts his right arm to release the ball. Justin Verlander and CC Sabathia have similar releases.

“Looking at the numbers, he has greater extension, he seems to move better with it, a lot of different things,” Strom said. “I’m just hoping it rekindles who he was.”

For Whitley’s next appearance, Strom’s scheduled a more extended outing. Whitley welcomes the change. He’s aware the optics of his spring seem peculiar.

Strom reiterated he’s “very excited” for Whitley’s promise and future major league standing. He lamented the “media hype on this guy” and wondered if perhaps it affects Whitley, who had a 12.21 ERA in Class AAA Round Rock last season.

“It’s so hard to look at this and say, ‘I’m doing well,’” Whitley said. “But this was my plan coming into spring training. I knew there was going to be some questions, but I’m sticking to my plan, and I’m proud of myself for it, even though I’m not blowing it out out there.”

“I’m not … striking out everybody, but I’m getting my work in and I’m making steps in the right direction. It stinks that all the stuff has to come with it in the next couple weeks, but I think it’ll be better in the long run.”

chandler.rome@chron.com

twitter.com/chandler_rome