PORTLAND – The kid is gone.

Xander Bogaerts, the best prospect the Boston Red Sox have featured in years, was promoted from the Portland Sea Dogs to Triple-A Pawtucket.

Bogaerts, 20, left Thursday morning and was penciled in the PawSox’s lineup Thursday night, scheduled to bat sixth and play shortstop. But the game was rained out.

Bogaerts will get to make his debut Friday and is expected to adjust well.

“One of the best I’ve ever had,” Sea Dogs Manager Kevin Boles said.

Others feel the same way, including Baseball America, which not only ranks him the Red Sox’s No. 1 prospect but the No. 8 prospect in all of minor league baseball.

Bogaerts, who turns 21 on Oct. 1, is believed to be the youngest player in Triple-A. He is the youngest everyday player to ever play for Pawtucket (pitcher Jeff Suppan was 11 days younger than Bogaerts when Suppan debuted for Pawtucket in 1995).

There was no need to rush Bogaerts because he is so young and isn’t on the Red Sox’s 40-man roster. But Bogaerts was playing too well to stay in Double-A. He batted .424 in June.

For the season, Bogaerts was batting .311 with six home runs. He had a .407 on-base percentage and .502 slugging average (.909 OPS).

“Obviously, No. 1, you notice the bat,” Boles said. “He was pitched extremely tough when he was here. And you can’t hide him anywhere in the lineup. They know who he is.”

Pitchers challenged Bogaerts with breaking balls, respecting what he can do with a fastball. Bogaerts adjusted and still performed.

“All the attention he got, he handled it beautifully,” Boles said.

In the field, Bogaerts made some sensational plays.

“The defensive potential, I think that gets kind of hidden, as far as how athletic he is out on the field,” Boles said.

Boles smiled as he talked. He has watched some good players come through his clubhouse (and Jackie Bradley Jr. stopped by for a visit Wednesday when Pawtucket was off).

Boles raved about Bradley last year. Now he can’t heap enough compliments on Bogaerts.

“It’s pretty impressive where this guy can be in a couple of years,” Boles said.

Kevin Thomas can be reached at 791-6411 or:

[email protected]

Twitter: ClearTheBases