For more than a quarter-century, the Arizona Fall League has helped prospects take the next step to becoming valuable and often elite-level big leaguers. The 2018 edition of the league -- which is in its 27th season -- will surely follow suit when it begins on Oct. 9. 
On Thursday, the AFL released its preliminary rosters, and they are filled with some of the best prospects in baseball. All 30 organizations feed the six teams in the league, and they have sent in an impressive group thus far, with rosters sure to evolve and change between now and October as each Major League team finalizes who is being sent to Arizona.
2018 Arizona Fall League rosters
In the preliminary rosters, there are 18 players on MLB Pipeline's Top 100 Prospects list, 11 in the Top 50, with the addition of Rockies top prospect Brendan Rodgers late Thursday afternoon. Overall, there are already more than 80 members of team Top 30 lists slated to participate in the six-week league.
It all starts with the No. 1 prospect in baseball, Vladimir Guerrero Jr., the Blue Jays phenom and son of the Hall of Famer of the same name. Guerrero flirted with hitting .400 for much of the 2018 season and heads to Arizona to make up for some at-bats lost to a left knee injury. He'll reunite in Surprise with organization-mate Bo Bichette (No. 9 on the Top 100). The only two members of the top 10 from the same organization played for much of the year together in Double-A. Rodgers, at No. 6, gives the AFL another top 10 hitter.
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The top-ranked pitching prospect is Astros right-hander Forrest Whitley, who comes in at No. 7 overall. He is part of a talented Scottsdale rotation that also includes Phillies right-hander Sixto Sanchez (No. 17 overall) as well as fellow Astro and 2017 first-rounder J.B. Bukauskus.
After Bichette, the top-rated hitter is Reds outfielder Taylor Trammell (No. 19 overall), followed by White Sox outfielder Luis Robert (No. 25) and Brewers second baseman Keston Hiura (No. 26).
"Every chance I get to play against some of the best competition in baseball, I'm excited to do it," said Trammell, the 2018 Futures Game MVP, who will also play for Scottsdale. "It's an honor and I'm blessed to compete some more for the year. It's going to be a fun time. I'm ready to get after it now.
"I've heard when you go there you're going to face some really good pitching, some pitchers who'll be in the big leagues next year. I get the chance to show people what I have. Some guys told me it's some of the best times you'll ever have playing baseball. Some said it helped them show what they needed to work on going into the next year."
The other Top 100 prospects so far in the AFL this season are Nationals shortstop Carter Kieboom (No. 34), Dodgers catcher Keibert Ruiz (No. 37), returnee Estevan Florial of the Yankees (No. 46), Braves outfielder Cristian Pache (No. 55), Mets infielder Andres Gimenez (No. 57), who is joined by organization-mate Peter Alonso (No. 61), Rangers outfielder Julio Pablo Martinez (No. 58), D-backs right-hander Jon Duplantier (No. 67) and another pair AFL return participants, Marlins outfielder Monte Harrison (No. 76) and Red Sox infielder Michael Chavis (No. 97).
Hundreds of future Major League All-Stars have come through the Fall League since its inception, including Mike Piazza, the first AFL alum to get enshrined in the Baseball Hall of Fame in Cooperstown. There have been 29 Rookie of the Year Award winners, 17 MVP Award winners (20 total awards, with Jose Pujols winning three) and six Cy Young Award recipients (eight awards, with Roy Halladay and Max Scherzer winning twice each) who put the finishing touches on their Minor League development in Arizona over the two and a half decades of the league's existence.
The AFL is owned and operated by MLB, and the league plays a Monday-Saturday schedule. The championship game will be played on Saturday, Nov. 17, at Scottsdale Stadium. The 13th Fall Stars Game is scheduled for Saturday, Nov. 3, at Surprise Stadium. Game times are 12:35 p.m. and 6:35 p.m. MT, with some noted exceptions in the schedule. The Bowman Hitting Challenge will be held at Sloan Park on Saturday, Oct. 13.
The Fall League's six venues remain Camelback Ranch-Glendale (Glendale Desert Dogs), Peoria Sports Complex (Peoria Javelinas), Salt River Fields (Salt River Rafters), Scottsdale Stadium (Scottsdale Scorpions), Sloan Park (Mesa Solar Sox) and Surprise Stadium (Surprise Saguaros).