Using the Top 100 list as a guide (with their current rank in front of their names), here are the top 10 prospects who could -- or perhaps should -- get the call to the big leagues once rosters expand, focusing only on Minor Leaguers who have yet to spend a day in the big leagues.
2. Shelby Miller, RHP, Cardinals: The overall numbers may not look pretty, but look more closely at how he's thrown in the second half of his Triple-A season. The right-hander has a 3.04 ERA over 53 1/3 innings and has allowed only 43 hits (.216 opponents' batting average) and seven walks while striking out 61. In five August starts, Miller has struck out 44 and walked just four in 31 1/3 innings.
4. Jurickson Profar, SS, Rangers: There's been buzz about the 19-year-old shortstop being called up to join fellow infielder Mike Olt in the big leagues to help the big league club down the stretch. He's not going to be called upon to play short every day with Elvis Andrus entrenched at that position, but Profar can help out with his bat, his legs and with his glove at second, short or even third in a pinch. Profar isn't on the 40-man roster, but that hasn't stopped the Rangers from promoting prospects in the past.
7. Dylan Bundy, RHP, Orioles: Machado, the No. 3 overall prospect, is already up and contributing in Baltimore. Could Bundy be next? Just a year out of high school, the right-hander has already reached Double-A, and the O's have carefully monitored his workload. In the long run, there's no question Bundy is a starter, potentially at the top of any team's rotation, but he could definitely contribute using his power stuff in short stints out of the bullpen as Baltimore makes a playoff push. He's on the 40-man roster, so that's one hurdle already cleared.
11. Danny Hultzen, LHP, Mariners: The No. 2 pick from the 2011 First-Year Player Draft was making a beeline for Seattle, having reached Triple-A Tacoma in late June. He hasn't been as dominant there as he was with Double-A Jackson, struggling with his walk rate, though he's still missed plenty of bats. Hultzen's on the 40-man roster, so if the Mariners wanted to give him a taste to motivate him for a shot at winning a big league rotation spot in 2013, it would make some sense.
14. Wil Myers, OF, Royals: He might fall under the "Why hasn't this happened yet?" category, but keep in mind that Myers is just 21 and is playing in Triple-A for the first time. An ill-timed slump just after his triumphant XM All-Star Futures Game appearance in Kansas City probably didn't help, either. The slugger isn't on the Royals' 40-man roster yet, but room might be made for the man with 35 home runs this season, one behind the Minor League lead.
17. Nolan Arenado, 3B, Rockies: There was a good deal of talk about Arenado making the big club out of Spring Training, but he wasn't quite ready and went to Double-A Tulsa instead. While Arenado hit fairly well there, his power and run production dipped quite a bit, causing some pause. But don't look now; Arenado has hit .333 and slugged .531 in August, and the group currently manning the hot corner in Colorado shouldn't be seen as a huge obstacle.
23. Carlos Martinez, RHP, Cardinals: OK, so maybe this is wishful thinking, considering he's only 20, he's not on the 40-man and he has just 14 starts above A ball. But stranger things have happened and Martinez's power stuff would look very good coming out of the bullpen for a month as the Cards chase the Reds.
26. Billy Hamilton, SS, Reds: He's only played shortstop and there's no place for him to play in Cincinnati, but just having Hamilton on the bench as a pinch-running threat should be enough to warrant a call. All Hamilton has done in 2012 is set the Minor League stolen-base record with 154 (and counting) while hitting for average and getting on base across two levels.
35. Hak-Ju Lee, SS, Rays: Tampa Bay hasn't really had an everyday shortstop all year. The Rays like their positional flexibility, so that's somewhat by design. But while Lee isn't going to step in and start at the premium position daily during a playoff hunt, he could provide defensive insurance and some excellent pinch-running skills for the final month.
36. Jake Odorizzi, RHP, Royals: The starter for the U.S. squad in July's Futures Game, Odorizzi was expected to reach the Majors along with Myers before long. Aside from his last outing, the right-hander has been very solid with Triple-A Omaha. Even though he's not yet on the 40-man roster, Odorizzi deserves an audition for 2013 and he'll have to be added this offseason or be left eligible for the Rule 5 Draft.
Other Top 100 prospects to watch: Gary Brown, OF, Giants; Jedd Gyorko, 3B/2B, Padres; Grant Green, OF, A's