The pitching prospects seemed to come in waves. Remember when the Portland Sea Dogs had the Fab Four of starters Anthony Ranaudo, Matt Barnes, Drake Britton and Brandon Workman in 2013?

The next group to filter through – although they did not all arrive at the same time – included Henry Owens, Brian Johnson, Eduardo Rodriguez and Steven Wright (the latter two coming in trades).

This year, the starting prospects are scattered. Portland has a group of young pitchers – led by Teddy Stankiewicz (1.13 ERA in four starts). Salem features the rising Travis Lakins, with the best Red Sox pitching prospect in Greenville, in Anderson Espinoza. Michael Kopech, who could be in Salem, is recovering from a broken hand.

A lot of pitchers. But one question remains.

Where is Trey Ball on the list?

Ball, 21, was drafted seventh overall in the 2013 draft – the highest draft choice the Red Sox had since they picked Trot Nixon seventh in 1993.

Handed a $2.75 million signing bonus, Ball reported to the rookie leagues as the Red Sox awaited his ascent.

It has not happened so quickly. But that is the gamble when you draft a skinny 18-year-old kid (6-foot-6, 185 pounds) and count on his development.

Ball is in advanced Class A Salem for a second straight year. His season was delayed by a knee injury and he made his 2016 debut last week (four innings, three hits, two runs, three walks, a hit-batter and five strikeouts).

Last year, Ball was 9-13 for Salem with a 4.73 ERA. In 1291/3 innings, he struck out 77 but walked 60.

“Sometimes, he’s inconsistent with his command,” said Sea Dogs Manager Carlos Febles, who managed Ball in Salem last season.

“He’s a young kid, but he’s a talented kid. Has a great arm.”

Might the Red Sox push Ball?

“As an organization, you put a guy where they can have success,” Febles said. “At some point, you’ll see this guy in the second half (of the Sea Dogs season).”

Ball features a fastball in the low 90s and a good change-up. The curve is getting there. He has not progressed as fast as other top pitchers out of high school – Owens, for example, was drafted in 2011 and reached Portland in 2013. But Boston can be patient. Ball is not eligible for the Rule V draft until after next season and will not be a minor league free agent until two years after that.

Want a positive sign? In his start last week, Ball got into a bases-loaded, no-out jam in the fourth. He recorded a strikeout, a forceout at home and another strikeout to squash the threat.

WHAT HAPPENED TO that Fab Four from 2013? None stayed in the Red Sox rotation, although Barnes is showing potential in the Boston bullpen, and Workman may join him once he’s fully recovered from Tommy John surgery. Ranaudo is starting in Triple-A with the Rangers, and Britton is a Triple-A reliever with the Tigers.

AS FOR THE NEXT foursome, Owens and Wright are in Boston’s rotation because of injuries to Rodriguez and Joe Kelly.

Owens figures to go back to Pawtucket when Rodriguez returns (he is scheduled to make a rehab start Tuesday in Triple-A).

Wright, however, is pitching too well to remove from the rotation and Boston has some decisions to make when Kelly is ready, possibly in two weeks.

Johnson made his major league debut last August, but then missed the rest of the season with elbow tightness. He’s in Pawtucket (2.25 ERA in four starts). If you were making a depth chart for this season, Johnson would be No. 8.

ANDREW BENINTENDI is another seventh overall draft pick by the Red Sox in last year’s draft. (All those last-place finishes were good for something, and Boston has the 12th overall pick this year.)

Benintendi, an outfielder, continues to show why he is one of Boston’s top prospects. He was named the Carolina League Player of the Week, batting .450 (9 of 20) in five games, with two doubles, a home run and 11 RBI. He also stretched his hitting streak to 19 games, the longest current streak in pro baseball.

LAKINS MAY NOT have been a big-name signing, drafted last year in the sixth round. But the right-hander from Ohio State is flying through the system. He pitched only one game (two innings) last year, with Lowell. He skipped Greenville and began his first full season with Salem.

In four starts, Lakins is 3-1 with a 2.13 ERA (3-0, 1.24 in his last three starts). With a lively fastball and developed change-up and curve, Lakins has struck out 27 and walked 10 in 251/3 innings.