Top prospects change hands at trade deadline time. Teams out of the running give kids a chance to show what they can do. Contenders look within for a boost down the stretch. Those players you've heard about, you get to see on the big-league stage. Some have been up before, others will be making their Major League debuts.
Already, several of the big-name prospects have made their presence known. Jay Bruce, Evan Longoria and Chris Davis are among the immensely talented young players now dotting big-league rosters and putting up numbers.
There'll be plenty more to come, especially once the rosters expand on Sept. 1. There's one caveat, though: the Olympics. Several players -- Colby Rasmus comes to mind -- who might have earned call-ups but will be spending two weeks or so in Beijing in August, thus putting off what likely will be the inevitable for many on that roster. With that in mind, here's a look at some players -- keying on on those on the MLB.com Top 50 prospects list at the start of the season -- who could be called up at any time to make an impact in the big leagues.
Gio Gonzalez, LHP, A's: The Angels are running away and hiding and the A's are trading established starters like it's going out of style. Nevertheless, Oakland is just six games out of the Wild Card and could be looking for rotation help. Dallas Braden is taking Joe Blanton's spot now and newly acquired Sean Gallagher will certainly get a nice long look, but should either falter, Gonzalez and his electric stuff could get a shot. He's been locked in of late, with a 0.81 ERA in three July starts, and could provide a burst of energy in the Bay area.
Fernando Martinez, OF, Mets: Yes, the Mets have been red-hot and are at the top of the NL East. But with all due respect, the combination of Marlon Anderson, Fernando Tatis, Endy Chavez and Nick Evans doesn't exactly thrill anyone, does it? The Mets are more likely to go the trade route to rectify that, but there have been rumors about the 20-year-old uber-prospect getting a call to provide a boost. He's actually been healthy for a stretch now, though it remains to be seen if he's ready to face big-league pitching.
Cameron Maybin, OF, Marlins: Remember him? Those upstart Marlins are only one game out in the NL East and they've been doing it with an outfield of less-than-stellar names. Maybin's past foray into the bigs didn't produce tremendous results and he's still learning the nuances of the game, but his speed and power combination are starting to come to the forefront and that kind of talent could be just the boost the Marlins need against the Mets and Phillies.
Andrew McCutchen, OF, Pirates: A look at the Pirates outfield may make one wonder where McCutchen might fit in and, as of right now, there isn't room. But unless you've been living under a baseball rock lately, the two corner outfielders in Pittsburgh have been perhaps the two most rumored-to-be-traded bats on the market. If the Buccos do end up trading Jason Bay or Xavier Nady, McCutchen could very well be the one to take their place.
Luis Pena, RHP, Brewers: He's not on any top-prospect list and he's "old" at age 25, but after seeing Pena throw in the Triple-A All-Star Game, it's hard not imagine him helping the Brewers bullpen at some point this year. Milwaukee is in the heat of the NL Central race with a bullpen that has posted a ho-hum 4.20 ERA and 16 blown saves. Pena's main nemesis has been control, but he hit triple-digits in that All-Star Game and a power arm like that should be able to contribute down the stretch.
David Price, LHP, Rays: Sounds like a reach, doesn't it? The No. 1 overall pick from last year's Draft didn't even make his pro debut until May of this year because of an elbow injury. There's no way the Rays would move him that quickly, right? They may not have a choice with the way he's been pitching. Already in Double-A, he's yet to lose a pro decision in 11 starts and has a combined 1.92 ERA, a .224 batting average against and 62 Ks in 65 2/3 innings pitched. He's already on the 40-man roster, courtesy of the Major League contract he signed last August, and the Rays might want his left arm to help out, even if it's in September. Tampa Bay does have the luxury of using other young arms like Wade Davis or Jeff Niemann as well.
Max Scherzer, RHP, Diamondbacks: Scherzer certainly did little wrong during his time in the bigs earlier this year, faring well in both starting and relief roles before getting sent down. He missed a month with shoulder fatigue and he's just getting back on the mound now, so it might take some time for him to build his arm strength back up. It's worth noting, though, that Arizona has the worst ERA, 5.72, in July. If that trend continues and Scherzer is back at full strength, seeing him up again would make a whole lot of sense.
Brandon Wood, 3B/Nick Adenhart, RHP, Angels: Both have been up and both have difficulties at the big-league level. Since getting sent down, Adenhart has struggled in Triple-A. Wood, on the other hand, has been hot, hitting .323 and slugging .600 in July. He might seem like a perennial prospect, but he's just 23 and has a ton of power. Adenhart has plenty of time to right himself as well. Even if it's just late in the year to give the regulars a rest, both these future Angels could help out the playoff drive in Anaheim.
Jonathan Mayo is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.