We continue and conclude our three-part series on the Best Young Players in Baseball. Unlike most prospect lists, players are categorized by age and major leaguers are also eligible for inclusion.

The methodologies are explained fully in parts one (25- and 24-year-olds) and two (23- and 22-year-olds). Today's focus is on 11 21-year-olds and 10 20-year olds.

All told, we ranked 75 players and gave honorable mentions to another 75. Of those ranked, 26 were pitchers or roughly 35% of the total (which is about pitching's proper proportional weighting with defense accounting for about 15% and offense the other 50%). Approximately two-thirds of the pitchers were righthanded and one-third lefthanded. There were 13 center fielders included, partly due to the fact – as you will read below – that the 21-year-old crop is overloaded with talent at that position (including seven of the top eight players). But it's also important to point out that many center fielders will end up in right or left field. Conversely, only three left fielders and four first basemen were chosen. It's nothing more than Bill James' Defensive Spectrum at work.

Interestingly, the National League had 38 players and the American League had 37. In both cases, that works out to about 2.5 players per team. The Milwaukee Brewers led all clubs with seven, including five players expected to be in this year's starting lineup and rotation. The Los Angeles Angels and Tampa Bay Rays had six each, while the Los Angeles Dodgers had five. Oakland brought up the rear with zero although it led the pack with eight honorable mentions, thanks to a couple of offseason trades that bolstered the club's pipeline of prospects. Houston, Philadelphia, Pittsburgh, San Diego, Seattle, Texas, Toronto, and the Chicago Cubs and White Sox had one each.

The Rays and Dodgers each had ten of the 150 ranked players and honorable mentions, followed by the Angels, Red Sox, and A's (all with 8). The Blue Jays (1) had the fewest and would get my vote as the worst collection of young talent in the game, follwed by the Astros, Cubs, and Giants (all with 2).

All in all, I believe the 25-and-under group is special by historical standards, albeit not up to the class of 1956 when Hall of Famers Hank Aaron, Luis Aparicio, Ernie Banks, Jim Bunning, Roberto Clemente, Don Drysdale, Al Kaline, Harmon Killebrew, Sandy Koufax, Mickey Mantle, Eddie Mathews, Willie Mays, Bill Mazeroski, Brooks Robinson, and Frank Robinson were all at a similar age.

AGE 21

1. Jay Bruce | CIN | CF

A+/AA/AAA | 576 PA | .319/.375/.587 | OPS .962

Bruce was Baseball America's Minor League Player of the Year in 2007. Over three levels, the lefthanded-hitting center fielder combined for 46 doubles, 8 triples, and 26 home runs. His 80 XBH and 306 TB ranked second in the minors. He also struck out 135 times or nearly once every four trips to the plate.

2. Cameron Maybin | FLA | CF

R/A+/AA | 385 PA | .316/.409/.523 | OPS .932

Maybin spent most of the year drilling High-A pitchers but failed miserably in his MLB debut (.143/.208/.265 with 21 SO in 53 PA) when he was rushed to Detroit in August. He was traded to Florida in the Miguel Cabrera package this winter. Maybin is a big, strong, athletic type who will succeed in the big leagues in due time. Of note, he was the second-highest drafted high schooler in 2005 at #10, ahead of fellow center fielders McCutchen (11), Bruce (12), and Rasmus (28).

3. Colby Rasmus | STL | CF

AA | 556 PA | .275/.381/.551 | OPS .932

Rasmus led the Texas League in home runs (29), extra-base hits (69), and runs scored (93), while hitting .312/.429/.624 in the second half. He also drew 70 walks and stole 18 bases. A bona fide five-tool player, Colby led off for Team USA at the World Cup in November. His spring will determine whether he starts the season in St. Louis or Triple-A Memphis.

4. Andrew McCutchen | PIT | CF

AA/AAA | 570 PA | .265/.329/.388 | OPS .717

McCutchen had a poor April and his season-long stats suffered accordingly. At 5-11, 170, McCutchen isn't nearly as big as Bruce, Maybin, and Rasmus. His game relies less on power and more on speed and defense. He stands a decent chance of getting his first look in the majors this summer.

5. Nick Adenhart | LAA | RHP

AA | 153 IP | 1.46 WHIP | 6.82 K/9 | ERA 3.65

A highly regarded high school pitcher, Adenhart suffered a major elbow injury during his senior year and fell all the way to the 14th round of the 2004 draft. He received a $710,000 bonus despite the need for Tommy John surgery that same summer. In three seasons of minor league ball, the 6-foot-4 righthander has allowed only 10 HR in 361 innings. He should be a fixture in a big league rotation in 2009 and could see some action in the majors during the second half this year if injuries dictate his call-up.

6. Jordan Schafer | ATL | CF

A/A+ | 626 PA | .312/.374/.513 | OPS .887

Although Schafer had a breakout minor league season last year, it wasn't totally out of the blue. Baseball America was on him eight years ago, naming him the nation's top 13-year-old in 2000. At worst, he should be a poor man's Grady Sizemore, a lefthanded center fielder who could be a 20 HR, 20 SB, Gold Glove-type in the majors.

7. Desmond Jennings | TB | CF

A | 448 PA | .315/.401/.465 | OPS .866

Jennings hasn't played at the same levels of his counterparts and his ranking is based in large part on tools and projection. He has plus-plus speed (77 SB in 97 attempts in 155 MiL games) and above-average power. Jennings has come a long way from 2000 when he was drafted in the 10th round and signed for just $150,000. He should arrive in the majors about a year after most of his fellow 21-year-old center fielders.

8. Austin Jackson | NYY | CF

A/A+/AAA | 555 PA | .304/.370/.476 | OPS .846

Jackson is interesting in that he hit .260/.336/.374 in the Sally League (A) and .345/.398/.566 in the Florida State League (High-A). An outstanding athlete, he can run, hit for power, and should be able to handle the defensive demands of center field at the big league level.

9. Jake McGee | TB | LHP

A+/AA | 140 IP | 1.12 WHIP | 11.25 K/9 | ERA 3.15

McGee has progressed as expected from Rookie ball in 2004 to short-season A in 2005 to Single-A in 2006 to High-A and Double-A in 2007. He has excelled at every stop along the way, striking out more than one batter per inning in each of the last four leagues. The southpaw has a plus fastball but still needs to develop a better breaking pitch and changeup to continue his ascension to the majors.

10. Aaron Poreda | CWS | LHP

R | 46.1 IP | 0.84 WHIP | 9.33 K/9 | ERA 1.17

A first round draft pick last June, Poreda had a terrific professional debut season. However, the 6-foot-6, 240-pound southpaw dominated Rookie ball as a 20-year-old and needs to show that he can handle players his age and above before gaining any more respect. Poreda has been known to light up radar guns as high as the upper-90s so he just may be the real deal. Stay tuned.

11. Bryan Anderson | STL | C

AA | 431 PA | .298/.350/.388 | OPS .738

Anderson bypassed High-A en route to Double-A as a 20-year-old all-star catcher just two years out of high school. His body of work includes Team USA and the Futures Game.

Honorable Mention: Michael Bowden, Carlos Carrasco, Daniel Cortes, Will Inman, Beau Mills, Cole Rohrbough, Ryan Tucker, and Chris Volstad.

AGE 20

1. Justin Upton | ARI | RF

MLB | 152 PA | .221/.283/.364 | OPS+ 62

Ranking #1 is nothing new for Upton. He was the first pick in the 2005 draft and was playing in the big leagues 19 months after signing with the Diamondbacks. An easy pick as the top 20-year-old, Upton is a couple of years ahead of the competition. He went 5-for-14 with two extra-base hits as Arizona's starting right fielder in the postseason despite being 15 months younger than any other player in the big leagues.

2. Clayton Kershaw | LAD | LHP

A/AA | 122 IP | 1.28 WHIP | 12.02 K/9 | ERA 2.95

Kershaw has been on the fast track since being drafted with the 7th pick in 2006. Considered by many as the best LHP in the minors, Clayton has outstanding stuff, including a low- to mid-90s fastball and a hammer curve. He still needs to work on his command and control but projects as a big league starter in a year and a potential ace shortly thereafter.

3. Travis Snider | TOR | RF

A | 517 PA | .313/.377/.525 | OPS .902

Snider led the pitcher-friendly Midwest League with a .525 slugging average, 35 doubles, 58 extra-base hits, and 93 RBI. He could be the best pure hitter in the minors this season. The only rap against him is his body (5-11, 245) although he is an average runner at this point and his arm is good enough to play in right field.

4. Lars Anderson | BOS | 1B

A/A+ | 580 PA | .292/.393/.446 | OPS .839

A high school draftee in 2006, Anderson began his professional career in 2007 at Single-A and was promoted to High-A before the season concluded. At 6-4, 215, the lefthanded hitter has the frame to hit for power as well as the approach to work counts and draw walks. He is easier to project than any 20-year-old hitter not named Snider.

5. Jordan Walden | LAA | RHP

R | 64.1 IP | 1.03 WHIP | 8.82 K/9 | ERA 3.08

According to Baseball America, Walden was the #1 high school prospect entering his senior season in 2006. The Angels nabbed him in the 12th round after his velocity fell into the 80s, signing him for $1 million as a draft-and-follow out of Grayson County Community College in Texas. His fastball has since returned, touching 100-mph in a championship game at Orem last season.

6. Matt Latos | SD | RHP

A- | 56.1 IP | 1.42 WHIP | 11.83 K/9 | ERA 3.83

Like Walden, Latos was signed as a draft-and-follow (Broward Community College in Florida). The Padres locked him up for $1.25 million hours before the signing deadline. His talent is on the raw side but his upside is evidenced by a powerful fastball that has been known to eclipse 95 on the gun. Latos K'd 74 batters in 56 1/3 innings in the short-season Northwest League.

7. Hank Conger | LAA | C

R/A | 335 PA | .289/.333/.466 | OPS .799

Conger posted a .290/.336/.472 line as a 19-year-old switch-hitting catcher in the pitcher-friendly Midwest League. There is little question that the kid can hit. Still needs to prove that he can handle the defensive chores behind the plate.

8. Jeremy Jeffress | MIL | RHP

A | 86.1 IP | 1.23 WHIP | 9.91 K/9 | ERA 3.13

Poster child for the million-dollar arm, ten-cent head. Milwaukee's #1 draft pick in 2006, Jeffress may have the best arm in the system but has tested positive for marijuana four times and will begin the 2008 season serving the bulk of the 50-game suspension levied against him last year.

9. Gorkys Hernandez | ATL | CF

A | 533 PA | .293/.344/.391| OPS .735

The Braves acquired Hernandez and Jair Jurrjens from the Detroit Tigers for Edgar Renteria. Hernandez, who played in the Futures Game last summer, won the Gulf Coast League's batting title in 2006 and the Midwest League's MVP in 2007 (even though he was thoroughly outplayed by Snider).

10. Nick Weglarz | CLE | LF

A/A+ | 540 PA | .274/.393/.498 | OPS .891

Defensively challenged, Weglarz will have to hit his way onto a big league roster. He has been compared to Justin Morneau for his size, handedness, and power potential. Like his fellow Canadian, Weglarz may wind up at first base.

Honorable Mention: Brett Anderson, Adrian Cardenas, Kasey Kiker, Chris Parmelee, and Chris Tillman.