1. Clay Buchholz, 23-Year-Old RHP
Clay Buchholz might just be the best pitching prospect in baseball, so he's a shoo-in for best Red Sox prospect. Buchholz to this point in his career has done everything right. Throughout the minors, he walked only 2.43 batters and struck out 11.23 hitters in every nine innings of work.
What makes Buchholz so special is the strength of his secondary pitches. The young pitcher's fastball sat in the low-90's for most of his career. At the end of 2007, however, Buchholz's fastball was sitting at 96 mph and it's his third best pitch. His arsenal of secondary pitches is what will likely make him an affective major league pitcher.
That arsenal includes two change ups, a curve ball, and a slider. His straight change up is his best out pitch. It sits at around 80 mph, about 15 mph off his fastball. Buchholz also possesses a strike out 12-6 curve ball which buckles the knees of hitters. For reference, see the last out of Buccholz's no-hitter, in which Nick Markakis sat helplessly with his bat on his shoulder.
2. Jacoby Ellsbury, 24-Year-Old CF
After being a World Series hero, winning the Rookie of the Year Award doesn't sound all that exciting. But going into the season, Ellsbury is one of the most likely candidates. He's all a team could ask for in a leadoff hitter and center fielder. He's a left-handed slap hitter, who consistently puts the ball in play, gets on base, and advances on the bases once he gets on.
Ellsbury's also a defensive center fielder worthy of taking over for Coco Crisp. While he's not quite at Crisps's level, he's still one of the best defensive center fielders in the majors. His arm is only average, but it's pretty accurate. After Crisp and Damon, any arm at all is an improvement.
As of yet, Ellsbury doesn't have much power, but he is young. If he eventually develops 15-20 home run power, he has the potential to be one of the best center fielders in the majors. But as of now, his OBP and speed work perfectly at the top of the Red Sox batting order, even if he isn't going to hit home runs.
3. Jed Lowrie, 23-Year-Old SS
Lowrie possesses the plate discipline typical of so many Red Sox position players. Over his minor league career, he's gotten on base at a rate of .386. What makes Lowrie especially valuable though, is his developing power.
Lowrie slugged over .500 last year in significant time at both Double-A and Triple-A. That degree of power is incredible for a middle infielder. In fact, only 5 middle infielders slugged .500 or batter last year at the major league level. Lowrie's power, combined with the fact that he's a switch hitter, makes him a valuable commodity. So the Red Sox might look to capitalize on his trade value while it is high.
Defensively, Lowrie is an average shortstop. He could be the Red Sox shortstop of the future, but the Red Sox would like him to improve on his throwing accuracy. If he is dealt to Minnesota, he would likely start the major league season as a second baseman where his throws would be shorter.
4. Justin Masterson, 22-Year-Old RHP
Like any sinkerball pitcher, Masterson's career success is difficult to predict. But Masterson isn't the typical sinkerballer. He allows very few hits or walks, and has struck out more than a hitter an inning at every stop but Lancaster, which is notorious for being hitter friendly. Masterson's upside is tremendous.
Similar to Derek Lowe, Masterson has shown great potential both as a starter and reliever. Masterson has the strange ability to vary the speed of his sinker from 84-94, and he gets an insane amount of ground balls. He has a good slider, and a work-in-progress changeup. If he develops those pitchers further, he could make a quality top of the rotation starter.
Even at this point in Masterson's development however, he may be able to play a major league role similar to that of Julian Tavarez. Based on a team's needs, Masterson could be an average reliever or a back of the rotation starter.
5. Ryan Kalish, 19-Year-Old CF
At only 19 years of age, Kalish is already a four-tool-athlete, with the build to possibly develop power as well when he ages. Kalish was just drafted in 2006, and the organization worked with him quite a bit prior to his 2007 season. The work appears to have paid off. Looking at Kalish's Single-A line of .368/.471/.540, you'd think he played at Lancaster, but he in fact put those numbers up over 87 at bats in Single-A Lowell.
Kalish is a very exciting player for his age. He's got all the raw talent, including the ability to steal 18 bases last year in 23 games. If he develops the mental aspect of his game to match his physical abilities, he could have a bright future. He probably projects best as a right-fielder for the Red Sox, given his strong arm. If the Red Sox are patient with him and give him a full year at every level of the minors, he might be ready to take over for Drew in 2012, or perhaps even sooner.