System Rankings: 21 and younger (20-11)

With Spring Training underway and the 2017 season rapidly approaching, MiLB.com looks at the state of all 30 farm systems and ranks them, according to certain changing criteria with each edition. This week, we focus on prospects who will be 21 or younger on Opening Day and consider the quality and quantity of top talent in each system. Part I can be found here. Part II is below:

 20. Milwaukee Brewers

An exciting group of first-rounders from the past few years boosts the Brewers system with right-hander Luis Ortiz at the top of the list. The club's No. 4 prospect was traded from the Rangers in the Jonathan Lucroy deal last summer and notched a 1.93 ERA in 23 1/3 innings over six starts for Double-A Biloxi. Fellow 2014 picks Isan Díaz and Kodi Medeiros are finding their footing following their third pro campaigns, 2015 first-rounders Trent Clark and Phil Bickford showed promise in their first full seasons and 2016 second-round pick Lucas Erceg tallied a .327/.376/.518 slash line between Rookie-level Helena and Class A Wisconsin in his pro debut. (Erceg also went deep twice in a Cactus League contest on Monday.) Interestingly, the Brewers do not have any highly ranked teenagers; all of their top 15 prospects are at or above 20 years old.

 19. Toronto Blue Jays

The youth movement in Toronto is led by a couple of prospects with familiar names. Top-ranked Vladimir Guerrero Jr. and ninth-ranked Bo Bichette comfortably adjusted to the Minors as teenagers in Rookie ball last year. Bichette batted .427 in 22 games with the Gulf Coast League Blue Jays, while Guerrero posted a .808 OPS as the youngest player in the Appalachian League at age 17. Toronto's top pitching prospect, Sean Reid-Foley broke out in 2016 by going 10-5 with a career-best 2.81 ERA in 115 innings (21 starts). In his first full season, Justin Maese notched a 2.94 ERA with 64 strikeouts and 15 walks in 82 2/3 innings over 15 starts.

 18. Cincinnati Reds

Third baseman Nick Senzel quickly proved why he was the second overall pick in last year's Draft. MLB.com's No. 26 overall prospect collected a .305/.398/.514 slash line in 68 games between Rookie-level Billings and Class A Dayton. Taylor Trammell showed off his 70-grade speed with 24 stolen bases in 31 chances, while teammate Tony Santillan displayed his 70-grade fastball for the Mustangs. The Reds signed highly touted Cuban right-hander Vladimir Gutierrez last September, just before he turned 21, and are ready for him to make his pro debut this summer. Senzel is the Reds' only top-100 prospect who will be 21 or younger on Opening Day, though.

 17. Philadelphia Phillies

The GCL Phillies made it to the league finals last year with a prospect-laden squad led by 2016 first overall pick Mickey Moniak (above). MLB.com's No. 19 overall prospect topped the team with 28 RBIs and 10 stolen bases in 14 attempts. Also at 18, Sixto Sanchez led the GCL Phillies with a 0.50 ERA in 54 innings while going 5-0 in 11 starts. Right-hander Kevin Gowdy and third baseman Cole Stobbe, both 19, round out the highly ranked GCL Phillies ready to take the next step. A couple levels up, Franklyn Kilomé showed off his above-average fastball with 130 strikeouts in 114 2/3 innings for Class A Lakewood.

 16. Seattle Mariners

It took a few weeks for Kyle Lewis to adjust to pro ball after the Mariners selected him 11th overall last June, and while he was in the process of improving, his season was cut short. Baseball's No. 29 overall prospect saw his average peak at .299 on July 19, but he also saw his pro debut end when he injured his knee that day and needed ACL surgery. Lewis appears to back on track and is looking at a midseason return. Meanwhile, the mighty Tyler O'Neill was claiming every award he could, collecting 24 homers and 102 RBIs en route to being named the Southern League MVP and the Mariners' Minor League Hitter of the Year. Seattle doesn't have a lot of young depth in their rankings beyond these two stars, keeping them in the lower half, but the pair can't be ignored either.

 15. Oakland Athletics

The A's system is rich with youth, especially at the top of their ranks. Oakland's top three prospects -- Franklin Barreto, A.J. Puk and Grant Holmes -- are all under 22 and represent the organization in the Top 100. MLB.com's No. 52 overall prospect, Barreto reached the Minors' top level last season at the age of 20, hitting .284/.342/.422 between Triple-A and Double-A. After being selected sixth overall last June, Puk displayed his 70-grade fastball with a 3.03 ERA in 32 2/3 innings for Class A Short Season Vermont. Holmes, who joined the A's at the trade deadline from the Dodgers last year, will look to bounce back after struggling in the hitter-friendly California League.

 14. Tampa Bay Rays

The Rays organization is full of young, talented position players, starting at the top with Willy Adames. MLB.com's No. 21 overall prospect got into a groove in his third pro season, collecting a slew of personal bests before turning 21 on Sept 2. Tampa Bay prospects have shown versatility with Jake Bauers and Josh Lowe each splitting time between the infield and the outfield, while 18-year-old Adrian Rondon may have to do the same at 6-foot-1 and slide from shortstop to third in coming years. Garrett Whitley, the Rays' 2015 first-round pick, bounced back from a hamstring injury in his pro debut to lead Class A Short Season Hudson Valley with 38 runs scored in 65 games while only making one error in the outfield. The Rays have room for more pitching depth with Austin Franklin being the only highly ranked hurler under 22.

 13. Washington Nationals

At 19, Victor Robles is primed to be the future of the Nats. MLB.com's No. 7 overall prospect oozes potential with 70-grade speed while tallying career highs across the board in his third pro season. Outfielder Juan Soto, 18, and shortstop Carter Kieboom, 19, had stellar pro debuts in the Gulf Coast League as the former hit .361 in 45 games for the Rookie-level Nationals before a late-season promotion to the New York-Penn League. Kieboom, a 2016 first-rounder, tallied a .452 slugging percentage in the GCL with 16 of his 33 hits going for extra bases. Back from Tommy John surgery, southpaw Jesus Luzardo is set for his pro debut, while Anderson Franco is healthy after a back injury delayed his 2016 season. On Robles alone, the Nationals could've worked their way into this middle group, but these additional interesting pieces nudge the system to No. 13.

 12. Chicago Cubs

The reigning World Series champs could already have some future rotation help at the lower levels in Dylan Cease, Trevor Clifton, Jose Albertos and Jose Paulino. Cease's well above-average fastball garnered him 66 strikeouts in 44 2/3 innings with Class A Short Season Eugene, while Clifton led the system with 129 punchouts in 119 frames for Class A Advanced Myrtle Beach. At the plate, Cubs fans need to look no further than outfielder Eloy Jiménez. Baseball's No. 13 overall prospect topped the organization with a .329 average and added 14 homers, three triples and 40 doubles in 112 games at Class A South Bend, becoming the Midwest League's MVP.

 11. San Diego Padres

Youth rules in San Diego, where 10 of the Padres top 15 prospects are under the age of 22. Undaunted by a midseason trade from Boston, No. 25 overall prospect Anderson Espinoza displayed his 70-grade fastball with 100 strikeouts in 108 1/3 innings at age 18. Southpaw Adrian Morejon did not make his debut in 2016 after being signed in July, but the Padres feel he is worth the wait and a tax penalty after spending $11 million to sign him. (It was more than the team's allotted spending pool.) At 19, Luis Urías hit a California League-leading .330 as the youngest player in the circuit, then jumped two levels to show he could hang in Triple-A as well, going 4-for-9 with a homer and three RBIs. Shortstop Fernando Tatis Jr. will be 18 for his second stateside season and could be positioned for a rankings jump if he continues to show more than the typical power for his position. There's a lot of potential energy from this young group that could send the Padres system as a whole flying up similar rankings in years (or even months) to come.