The next great Boston Red Sox prospect may be stopping by Portland sometime in 2015.

According to multiple reports, the Red Sox and 19-year-old Cuban infielder Yoan Moncada have agreed on a contract that will include a $31.5 million signing bonus.

The Red Sox have yet to announce the deal. That could come as early as Tuesday, pending completion of the contract and a physical.

Moncada, who turns 20 in May, is not expected to be ready for the major leagues. He will begin 2015 in the minors, possibly as low as Class A, and then work his way up – including time with the Double-A Portland Sea Dogs.

But all of that is speculation until Boston makes the deal official.

“I can’t say much, other than we’ve been involved in evaluating him,” Red Sox General Manager Ben Cherington told Comcast Sportsnet.

Moncada was recently declared a free agent and reportedly worked out for 10 major league teams. The Red Sox and Yankees were among the teams that made offers. The New York Post reported the Yankees’ offer as $27 million.

Boston’s investment is actually doubled. Because the Red Sox have already spent more than allowed in bonuses for international players, they have to pay a 100 percent tax on the $31.5 million.

So the bottom line is a $63 million for Moncada. That is more than the $51.1 million Boston spent on the rights for Japanese pitcher Daisuke Matsuzaka in 2007.

But unlike Matsuzaka, as well as previous Cuban free agents Jose Iglesias (signed in 2009) and Rusney Castillo (signed last August), Moncada will not command a major league salary right away. He is expected to be sign a minor league contract. And when Moncada reaches the majors, Boston will have him for at least six years before free agency.

How good is Moncada? When news surfaced of the reported agreement, Baseball America national writer Ben Badler sent out this tweet:

“Once it’s official, Yoan Moncada immediately becomes Boston’s No. 1 prospect, and No. 10 in baseball.”

Baseball America annually ranks prospects in every organization. Former Sea Dogs catcher Blake Swihart is currently the Red Sox’ No. 1 prospect.

Moncada played in Cuba’s top league the past two years, batting a combined .277, with a .768 OPS (combined on-base and slugging percentage). He is a switch hitter and reportedly strong at 6-foot-2, 205 pounds.

In Cuba, Moncada played primarily second base, although he can also play shortstop and third base.

It’s conceivable Moncada eventually plays third base if newly signed Pablo Sandoval moves to first or designated hitter later in his career.

But that’s the future. Once Moncada’s expected signing is complete, Boston needs to place him with a minor league team. When Iglesias began pro ball with the Red Sox in 2010, he was 20 and the organization sent him to the Sea Dogs. But Iglesias was already on the team’s 40-man roster.

Castillo, already an advanced player at 27 when he signed, was in Boston by September.

The Red Sox could start Moncada in Class A – either Greenville, South Carolina, or the advanced A league in Salem, Virgina. That would help him acclimate to American ball – while avoiding the cold spring temperatures in Portland.

If Moncada is sent to Class A and excels there, then the Red Sox will give him a ticket to Portland. There, Hadlock Field fans can see for themselves what $63 million gets you these days.

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

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Twitter: ClearTheBases