If you're playing beyond the regular season as a professional baseball player, it generally means one of three things.1) You're new to the pro game with much to learn.2) You've been around for some time but haven't learned (or shown) enough, so you need to stay on your grind and try to open some eyes to ensure an invite to spring training the following year.3) You're what those inside the game affectionately call a "yard rats" -- someone who loves the game with such passion you can never get enough.A's outfield prospect Michael Choice is a combination of Nos. 1 and 3, and his talent level is such you don't often find in yard rats. A 21-year-old center fielder selected out of the University of Texas-Arlington with the 10th overall pick in the 2010 draft, Choice appears to have quite a steep learning curve, too.Among the 20 or so Oakland farmhand putting in organized overtime this offseason, Choice is -- by far -- enjoying the most success.Choice, who belted 30 home runs with 82 RBIs, a .376 on-base percentage, 28 doubles and a .916 slugging percentage while batting .285 for the Single-A Stockton Ports this season, hasn't cooled off a bit while playing in the desert sun for Phoenix of the Arizona Fall League. In 15 games and 39 official at-bats through Wednesday, Choice was batting at a .359 clip and a .444 OBP, five homers, three doubles and nine RBIs.Another of Oakland's top prospects, 24-year-old shortstop-turned-oufielder Grant Green, also plays for the AFL's Desert Dogs. Selected 13th overall out of USC in the 2009 draft, Green batted .291 with a .343 OBP and 43 extra-base hits at Double-A Midland this season, and through Wednesday he was batting .276 with a .317 OBP, four doubles, a triple, two homers, eight RBIs and 12 runs scored in 14 games in the AFL.Also playing in the AFL for Oakland are shortstop Dusty Coleman, catcher Ryan Ortiz, and pitchers Anthony Capra, Andrew Carignan, Murphy Smith and Tyson Ross.Ross, a 6-foot-6 righty out of Cal who spent part of the past two seasons with the A's but missed most of last season with an oblique injury and shoulder issues, has made four appearances for the Desert Dogs, allowing four runs on 10 hits and two walks while striking out eight over eight innings.Another Athletics who spent time in the bigs this year, first baseman Brandon Allen, is playing in the Dominican Winter League, batting .115 through his first 10 games, while utilityman Adam Rosales, who was limited by injuries to 24 games with Oakland this season, has played in seven games in Mexico. Catcher Eliezer Mesa and pitchers Graham Godfrey, Lenny DiNardo, Jordan Norberto, Jonathan Ortiz, Jose Guzman and Polin Trinidad also are among Oakland farmhands listed on DWL rosters. Ortiz, a righty who posted a 4.02 ERA while striking out 60 against 24 walks over 42 outings at Midland this year, has pitched in six games thus far for the Licey Tigers and has a 1.80 ERA.Pitchers Andres Aviles and Carlos Hernandez are playing in Mexico.