The Spencer Howard Experiment is returning to the minor leagues.

For at least the fourth time since spring training began, the Phillies’ plan for their top pitching prospect is changing. They optioned Howard to triple-A Lehigh Valley on Tuesday with the intention of continuing to build his workload as a starter and finishing off his development before plugging him back into the rotation.

Howard said he wasn’t given a timetable for when he may return.

“I think, long run, it’ll be for the better,” he said. “To me it all makes sense. Now that I get to go down and focus on developing and, not putting the team in jeopardy, but not having to worry about contributing to win games.”

Howard completed the fourth inning in only two of his five starts after getting called up last month. He topped out at 68 pitches. Although opponents were 4-for-39 (.103) with five walks and 13 strikeouts against the 24-year-old right-hander one time through the order, he had trouble the second time around, giving up six hits and six walks in 25 plate appearances.

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The Phillies skipped Howard’s turn in the rotation last week, and when he took the mound Monday night in Cincinnati, it was more or less as an opener. With lefty Matt Moore returning from the injured list and throwing five scoreless innings against the Mets last Friday night in New York, the Phillies had a replacement at the ready.

At last, though, it seems they are content to keep Howard in triple A for a while.

Howard was told the Phillies plan to keep him on a normal five-day schedule and stretch him out to 100 pitches per start. Pitching coach Caleb Cotham said he wants Howard to refine his off-speed pitches. Howard believes he was getting by early in games by throwing mostly fastballs. But once he needed to get to his off-speed pitches, opponents teed off, going 3-for-11 against his changeup and 3-for-9 against his slider.

“You can bully your way through a lineup just with the fastball. Second time through is when you really need to get them off of that,” Howard said. “So that’s when the off-speed, for me at least, comes into play. If I can just mix some of that in and get them to respect the fact that it is there, it will make my fastball better.”

It’s all part of the development process. But by president of baseball operations Dave Dombrowski’s admission, the Phillies had multiple goals for Howard this season.

The top priority was to build Howard’s workload after he threw less than 100 innings in 2019 and 24⅓ in the majors during the shortened 2020 season. They also wanted him to contribute at the major-league level before he reaches an innings cap that Dombrowski and manager Joe Girardi have declined to divulge.

Howard went to spring training in February to compete for a spot in the rotation. At the end of March, he was on his way to triple-A to be used mostly out of the bullpen. A month later, the Phillies decided to build him up more as a starter, and by mid-May, he was in the major-league rotation, taking the place of ineffective No. 5 starter Chase Anderson.

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“Sometimes we do things because we need someone to fill a spot,” Girardi said. “Or sometimes somebody goes down and we need to call up a young player that maybe is not completely finished off [developing]. He was a young pitcher when he got called up. We had a strange year last year. He’s not a guy that’s ever logged 150 innings in the minor leagues just because he moved fairly quickly.”

Now, it seems Howard will get a chance to focus solely on his development. Unless, of course, the Phillies’ plan changes again.

“Obviously I would want to be here over Lehigh, but I’m just trying to think big picture of going back and getting everything dialed in,” Howard said. “I know for sure that long term it’ll be good.”

Herrera out of lineup

Lefty-hitting center fielder Odúbel Herrera wasn’t in the lineup Tuesday night against Marlins lefty Trevor Rogers after starting 15 of the last 16 games.

Herrera made a costly mistake on the bases in the first inning of Monday night’s 12-4 loss in Cincinnati. He was thrown out at the plate when he broke for home on Bryce Harper’s one-out, two-on grounder to first base.

“There’s a lot put on Odúbel here, but a sac fly gets him in, too, a base hit gets him in, too,” Girardi said. “The first baseman was fairly close. That’s the bottom line. And you have to be a little bit less aggressive.”

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Extra bases

Second baseman Jean Segura took Howard’s roster spot after being reinstated from the injured list, as expected. Segura, who was leading Phillies regulars with a .332 average entering Tuesday night, missed two weeks with a strained left groin. ... Aaron Nola (5-4, 3.97 ERA) will start Wednesday night. The Marlins have not named a starter.