MLB.com's Jonathan Mayo breaks down the players reported to be heading from the Red Sox to the Padres in the pending Adrian Gonzalez trade:

Casey Kelly

The 2008 first-round Draft pick out of high school in Florida, Kelly is the son of longtime coach Pat Kelly, so he entered pro ball with an advanced knowledge of how to carry himself and play the game. A shortstop and a pitcher as an amateur, the Red Sox allowed him to hit and pitch in his first full season. He went 7-5 with a 2.08 ERA on the mound in 2009, representing the Red Sox in the All-Star Futures Game that July. After he reached an innings limit, he switched gears and played shortstop every day in the second half, hitting .222/.302/.340 over 57 games. After playing short in the Arizona Fall League, Kelly and the Red Sox decided his focus would come on the mound. That's where he spent all of 2010. While he went just 3-5 with a 5.31 ERA in 95 innings, he was doing so with the challenge of having been pushed all the way up to Double-A Portland at age 20.

He made four appearances in the AFL this past fall, and while again the results weren't great (6.75 ERA, 19 hits over 16 innings), scouts still had good things to say about his pure stuff. MLB.com's No. 28 prospect heading into the 2010 season, Kelly is still believed to have a very bright future. He throws a fastball up to 92 mph, though he's struggled with fastball command, one of the reasons for his poor results. He's got a plus curveball, thrown 77-81 mph, again with below-average present command. He's already got an average changeup, thrown 81-84 mph. He may never be the ace of a rotation, but with his three-pitch mix, pitching know-how and age, he could be a solid middle-of-the-rotation starter for years to come. Considering he's been a pitcher for only one full season, he could have a ceiling as high as a No. 2 in the not-too-distant future.

Anthony Rizzo

The Red Sox drafted Anthony Rizzo in the sixth round of the 2007 First-Year Player Draft, giving the Florida high school product an above-slot $325,000 to sign. He was off to a wonderful start in his first full season, in 2008, but his season ended after just 21 games when he was diagnosed with Limited Stage Classical Hodgkin's Lymphoma. He came back with a strong showing in '09, hitting .297/.368/.461 with a dozen homers and 66 RBIs in 119 games across both levels of A ball. He took another step forward in '10 with 25 homers and 100 RBIs, while hitting .260 and making it up to Double-A for the first time.

Rizzo has plus raw power that started to show up production-wise big-time this past season. He also gets graded out as a future plus hitter, with a good approach at the plate. He's a below-average baserunner, but is a plus defender at first base. He's got tremendous makeup and a strong work ethic, something that allowed him to come back from his illness so strongly. He's a solid-average-to-plus prospect overall with the chance to be a very good everyday first baseman one day. Give him perhaps a year and he could be a long-term replacement to Adrian Gonzalez at first base in San Diego.

Reymond Fuentes

The cousin of Carlos Beltran, Fuentes was the Red Sox's first-round pick out of the Puerto Rico high school ranks in the 2009 First-Year Player Draft.

The center fielder is a plus-plus runner on both sides of the ball, stealing 42 bases over two years in the Gulf Coast League and the South Atlantic League. Though Fuentes has below-average arm strength, he's very accurate with his throws. He's a plus defender with plus range.

Offensively, Fuentes has the chance to be an average hitter with average power as he matures. He's a premium athlete with the potental to be a toolsy, everyday center fielder at the big league level. With the GCL Red Sox and Class A Greenville Drive, he had a .270 average with five homers and 41 RBIs.