• Rookie — Usually young players just out of high school or college, with an average age of 19. Called “extended spring training” by MLB clubs.
• Short Season A — Most college draft picks go here for their first season. The team usually only plays for half the year, as it is filled with new draftees who don’t come in until June (the rest of the minor leagues start spring training in March).
• Class A — A step above the rookie team. Some major league teams have both “Low-A and “High-A” or “Advanced A” clubs playing in two different leagues for players are not prepared for the 140-game grind. • • Low-A — Usually younger guys who excelled in rookie or short season leagues. This is the make or break year for many. High-A features the biggest jump in talent. Only the best of the lower level minors, independent and college players make it here.
• Class AA (Double-A) — More experienced (and consistent) players (average age is 23) who are more likely to jump to the majors. AA teams may include former major leaguers who are there temporarily to recover from an injury or work out a performance problem before returning to the big club.
• Class AAA (Triple-A) — A step just below the MLB. The quality of the baseball here is very close to what fans might see at a major league game. The rosters here include older guys who have been up and down once or twice before and are roster fillers for the big leagues.
Note: More impact players jump from the AA to the majors than the AAA.
Although some baseball stars are drafted or signed to contracts and go straight to the majors, they are the exception to the rules. Most players play at least one minor league season. Occasionally, exceptional players, such as former Durham Bull Andruw Jones (now a centerfielder for the Atlanta Braves), goes through all the farm teams in one season and wind up in the majors the following season. Bryce Harper, Mike Trout and Manny Machado also needed limited minor league time.