When the Red Sox let Xander Bogaerts walk in free agency, the prevailing sense was that Boston had lost the four-time All-Star for nothing. The club got a compensatory draft pick, but because the club was over the luxury tax that season, the pick came after the fourth round, long after the premier talents are usually gone.

Little did anyone know, that pick wound up becoming one of the biggest success stories in recent minor league history.

Kristian Campbell, who the Red Sox selected with that compensatory pick last summer, enjoyed a stunning rise from relative afterthought to minor league superstar in his first full season as a professional. He’s gone from outside Boston’s top 30 prospects to within the top 25 in all of baseball, and Tuesday he was honored as Baseball America’s Minor League Player of the Year.

Campbell, a 22-year-old second baseman, was the top hitter in minor league baseball this season. He batted .330 with a .997 OPS, hit 20 home runs and stole 24 bases in 115 games across all levels. His advanced metrics were off the charts as well, and he performed at an elite level from High-A all the way to Triple-A.

Baseball America notes that a breakout like Campbell’s is virtually without precedent.

“Since the Prospect Handbook launched in 2001, Campbell is the first Minor League POY who did not rank among his organization’s preseason Top 30,” Baseball America writes. “This wasn’t a misevaluation by the entire industry, but rather a testament to Campbell’s work ethic and the advances in Red Sox hitting development.”

Campbell’s progress can be attributed in part to his gains in the Red Sox bat speed training program. By increasing bat speed and making other improvements he’s gone from someone viewed as a speedy contact hitter to someone who boasts enough power to potentially top 20 home runs a year in the majors.

That progress, and the attendant on-field results, are a big part of why Campbell now ranks as the No. 24 prospect in MLB according to Baseball America’s latest Top 100 rankings.

The Baseball America honor is one of many accolades Campbell has earned recently. He was also named Eastern League MVP for his performance at Double-A Portland, and he was one of four Red Sox prospects honored as Eastern League All-Stars, along with fellow top prospects Roman Anthony, Marcelo Mayer and Kyle Teel.