Whenever a prospect in the minor leagues begins to prosper, all the armchair general managers want him promoted.

With Mookie Betts tearing up the Eastern League as a leadoff hitter, some Red Sox fans wonder why he isn’t rushed up to Boston, which obviously needs a little offensive help.

“Too early” came the answer from reasonable voices.

But maybe it’s time for the Portland Sea Dogs to say goodbye to Mookie, who looks ready for at least the next level.

Betts, 21 and with only 45 games of experience in Double-A, may be headed to Triple-A Pawtucket based on how the Red Sox handle their top prospects.

And Betts should not be the only one promoted. He’s just the biggest name of the bunch.

First baseman Travis Shaw could be packing up his gear, maybe even starting pitcher Keith Couch. And a handful of relievers could go at any time.

How do the Red Sox decide when a player is ready to go? The organization doesn’t announce its timetable but we can see a pattern of promotions based on two categories.

One group includes special prospects.

The second contains players who have consistently shown they are ready to move up.

Betts is part of the first group, special players that can impact a team with their talent, regardless of age.

Previous special players have included Dustin Pedroia, Jacoby Ellsbury, Jackie Bradley Jr., Xander Bogaerts and Garin Cecchini.

Look at how many games they played for the Sea Dogs: Pedroia (66), Ellsbury (67), Bogaerts (79), Bradley (61) and Cecchini (66).

So the guess here is Betts has less than three weeks left with the Sea Dogs – maybe much less based on how he’s consistently excelling: .361 average, .443 on-base percentage, 1.015 OPS (combined on-base and slugging averages), six home runs and 20 stolen bases.

Betts is a marvelous second baseman but his occasional games played in center field (because he isn’t playing second base in Boston with Pedroia there) shows the Red Sox are getting him ready to move on.

Shaw, 24, is part of that second group, a proven player in Double-A ready for the next challenge. Shaw arrived in Portland at the end of the 2012 season. He struggled last year but is breaking out in 2014: .310 average, .411 OBP, .959 OPS, 10 home runs, 35 RBI.

Shaw has played over 200 games in Double-A. He is a gifted fielder and there’s no established first baseman in Pawtucket. His promotion seems inevitable.

Couch, 24, is knocking on the Triple-A door but Pawtucket is full of starting prospects. Maybe with Brandon Workman moving up to start for Boston on Sunday in place of the injured Felix Doubront, Couch will get his chance.

Couch didn’t arrive in the pros as a prime prospect (15th-round pick in 2010 out of Division II Adelphi University). But he’s shined in Double-A. He made 29 appearances last year, 15 as a starter. This season he’s 6-0 with a 2.39 ERA.

When there’s an opening, Couch figures to be the first called up to Triple-A.

Portland features at least four relievers who could move up this year. Noe Ramirez is the prospect, with a 2.08 ERA and 0.96 walks/hits per inning ratio (WHIP). Joe Valdez (1.69/1.31) has major league experience. Michael Olmsted (3.86/1.59) has been in Triple-A, and Miguel Celestino (2.45/1.15) is improving command of his electric fastball.

A couple other players may get a shot with Pawtucket. Utility player Derrik Gibson and outfielder Shannon Wilkerson are in their third season with the Sea Dogs and performing well, Gibson batting .295, Wilkerson .294.

Shortstop prospect Deven Marrero can play in the majors right now based on his defense. His offense is coming around (batting .278). If that continues, he should see Pawtucket this summer.

Catching prospect Blake Swihart is batting .286. He figures to be in Boston’s plans but the Red Sox want to bring him along sensibly, much like catcher Christian Vazquez staying most of last year in Portland.

Sea Dogs fans can watch a slew of prospects, but especially in the case of Betts and Shaw, they won’t be here much longer.

VOTING FOR the Eastern League All-Star Game has begun. Fans can note via the internet (www.seadogs.com) through June 27. The game is July 16 in Altoona, Pennsylvania.

THE SEA DOGS return to Hadlock Field on Tuesday. The franchise, in its 21st season, expects to welcome its 8 millionth fan Tuesday.

That fan will receive seven prizes, including two season tickets for the next eight years, a Sea Dogs jersey, golf passes and gift cards.

Kevin Thomas can be reached at 791-6411 or at:

[email protected]

Twitter: ClearTheBases