September callups make for September fun, especially if your team is out of the playoff chase. There are other prospects, however, who arrived prior to Sept. 1 and have been making a case for a major league role in 2009.

Boston’s Jed Lowrie was summoned in mid-July, and no rookie can top his 28 RBIs since the start of August. Only six American League players have more ribbies in this span. Lowrie is making his case to join the Red Sox infield next spring.

Reds phenom Jay Bruce has eight home runs since Aug. 1, and that’s the most among his rookie peers. He’s batting just .239 in this stretch, but the 21-year-old outfielder has more than doubled his home-run total and has 14 in 97 games with Cincinnati.

Red Sox prospect Brandon Moss didn’t have much chance of playing in Boston, but then he was dealt to Pittsburgh in the Manny Ramirez-Jason Bay blockbuster at the trade deadline. Although he’s batting just .257 since the move, he’s shown plate patience and his power has started to emerge. He’s stroked six doubles and five home runs in his last 22 games.

Rangers rookie Chris Davis could develop into a middle-of-the-order slugger, and he was promoted in late June after hitting .333-23-73 in 77 games between Double-A Frisco and Triple-A Oklahoma. He’s taken his power stroke to Texas. The corner infielder has recorded 17 doubles and 14 home runs in 61 games. In 15 contests since Aug. 18, Davis has hit at a .340 clip with seven doubles, three homers and 10 RBIs.

After three seasons in Class-A ball, Giants prospect Pablo Sandoval broke through in 2008, batting .350-20-96 in 112 games between high Class-A San Jose and Double-A Connecticut. The catcher-corner infielder hasn’t slowed down since an Aug. 13 promotion. The 22-year-old switch-hitter is batting .353 with four doubles and two home runs in his first 18 major league games.

Florida catching prospect John Baker started 9-for-47 (.191) in July after batting .321 and slugging .497 in the Triple-A Pacific Coast League. Since July 30, however, the 27-year-old left-handed batter is hitting .346 (28-for-81) with 14 RBIs and a .443 OBP in 27 games. He’s 8-for-12 in his last four contests.

There are numerous others who have made a case for a major league role in 2009, long before September rolled around. These guys are worth watching, too, during the season’s final month.