A rookie may have one foot in the door to big league success, but we like to think he still has his other foot in the prospect pool. So in what has become a midseason tradition, we bid adieu to young players whom we no longer get to cover in print or in cyberspace, not because they're unworthy but because they have lost prospect eligibility.

You may notice that this year's format is slightly altered. Rather than count down the top 20 rookies, we've organized the top first-half performers into a team—five starting pitchers, three go-to relievers, eight position players plus a DH. This results in a few notable omissions, such as Cubs corner outfielder Tyler Colvin, Rays righthander Wade Davis, Indians shortstop Jason Donald, Indians righty Mitch Talbot and Pirates second baseman Neil Walker. But we may hear from them, as well as stud catcher Carlos Santana, in our end-of-season top rookies feature.

Rookies are organized into four groups so that performances can be compared more directly. Players are divided into starting pitchers, relief pitchers, up-the-middle defenders and corner players, because no one ought to expect a middle infielder's raw offensive production to look like a corner outfielder's.

For rookie rundowns going back four years, check out the 2007, 2008 or 2009 midseason lists.

An asterisk (*) denotes a lefthanded batter or thrower and a pound sign (#) signifies a switch-hitter. Stats through July 11, to provide an all-star break snapshot.

UP-THE-MIDDLE ROOKIES
Catcher, Second Base, Shortstop & Center Field

C—Buster Posey, 23, Giants

When baseball recessed for the all-star break, Posey had started just 10 games at catcher. The rest of the time he played first base. But because of his incendiary hitting and the fact that he finished the first half as the Giant's starting catcher, starting seven of his final nine games there in the wake of Bengie Molina's trade to Texas, Posey gets the nod over the Rays' John Jaso. (See the comments for more on Jaso.) He's hit so well, in fact, that the Giants feel like they've added a big bat at the trade deadline. And not only has Posey nabbed 43 percent of basestealers, but he's handled a sinister pitching staff that included the varied styles of Tim Lincecum, Matt Cain, Jonathan Sanchez, Barry Zito and Brian Wilson. 

Since the break: Posey has found another gear, going 19-for-45 (.422) with a home run, four doubles and eight RBIs. It's all part of an awesome July in which he's hit .459/.500/.788 in 85 at-bats since assuming the starting gig.

2B—Reid Brignac, 24, Rays

In addition to Brignac, the Rays have integrated an entire brigade of productive rookies and sophomores, including Wade Davis, John Jaso, Matt Joyce, Jeff Niemann, David Price and Sean Rodriguez. For his part, Brignac offers the defensive versatility to fill in at either middle infield position, while offering a lefthanded-hitting option for either second baseman Rodriguez or shortstop Jason Bartlett. He hangs in well versus lefties (.863 OPS), though an uppercut in his swing leads to strikeouts in about 25 percent of his at-bats.

Since the break: Brignac has clubbed four home runs in 20 at-bats, going 9-for-20 (.450) overall.

SS—Starlin Castro, 20, Cubs

The Cubs have endured Castro's growing pains—he sports a .953 fielding percentage and already has a three-error and a two-error game—but his talent is nevertheless obvious. His explosive bat speed and easy actions at short send not-so-subtle reminders of why he's a big league regular at age 20. But how rare is that? In the past 25 years, the only other shortstops to accrue 200 at-bats at ages 19 or 20 are Elvis Andrus, Jose Lopez, Edgar Renteria, Jose Reyes and Alex Rodriguez. And with the exception of A-Rod, Castro has out-hit all of them. 

Since the break: Castro has opened the second half on fire, going 20-for-42 (.476) with six doubles, a triple, a home run and only one strikeout. That's a .738 slugging percentage over a week-and-a-half stretch. His average shot from .270 to .307.

CF—Austin Jackson, 23, Tigers

Jackson may not have true plus power or speed, as defined by the scouting scale, but the man sure can hit for average and defend the heck out of center field. He can throw, too, giving him five average-to-above tools. Now consider that he bats leadoff for a team in the thick of the AL Central race and Jackson has made the Tigers forget all about his predecessor Curtis Granderson, who has hit .244/.315/.491 in Yankees pinstripes.

"He has produced quicker than most people thought, I think," a pro scout for an NL organization said. "He's making that trade look very good for (the Tigers) right now."

Jackson debuts just a year after the ’09 rookie class gave us Dexter Fowler, Andrew McCutchen, Colby Rasmus and Drew Stubbs. What's more, veterans like Adam Jones, Matt Kemp, Denard Span and Chris Young are not yet 27 years old.

Since the break: The hits keep coming for Action Jackson, who has gone 20-for-45 (.444) with three doubles, three triples and two steals (in three attempts).

ON-THE-CORNER ROOKIES
First Base, Third Base, Left Field, Right Field & Designated Hitter

1B—Ike Davis, 23, Mets

The Mets struggled to replace Carlos Delgado's production in ’09, turning primarily to Dan Murphy, who wound up leading the team with 12 home runs even while he compiled a modest .741 OPS. Enter Davis, who zoomed to New York less than two years after being drafted. He's endured own growing pains of his own, but he's sure-handed around the bag and he can drive the ball as far as just about anyone. If Davis can rein in the strikeouts with experience, he could be a 30-homer threat in time.

Since the break: Seven of Davis' nine hits have gone for extra bases (three homers, four doubles), but over 46 at-bats that equates to a .196 average. The 16 strikeouts have not helped.

3B—David Freese, 27, Cardinals

A St. Louis native, Freese may lack prototypical power for a corner infielder, but he's hit for average at every level—.299 in the big leagues, .304 in Triple-A and .302 in high Class A, the three levels at which he's spent appreciable time. Despite his hitting résumé, gap power and serviceable defense at third, Freese has failed to establish himself because injuries keep getting in the way. Last year, he had surgery in May to repair an ankle that he originally injured in an offseason car accident.

Since the break: Freese has not batted in the second half and could be out until mid-August or later. He broke his left big toe when he dropped a weight on his foot.

LF—Brennan Boesch, 25, Tigers

The Double-A Eastern League's reigning home run champ, Boesch entered the year as more statistical oddity than projected regular. But then he hit .379/.455/.621 in two-plus weeks with Triple-A Toledo, earning him a piece of the big league job. Boesch seized the opportunity and finished the first half as the rookie leader for home runs, RBIs, average, on-base percentage and slugging.

Since the break: Boesch has walked seven times and struck out five, but otherwise he's collected just four singles in 36 at-bats, good for a .111 average.

RF—Jason Heyward, 20, Braves

The game's top prospect heading into the season, Heyward jumped seamlessly into the thick of the Braves' lineup. If anything, we undersold his potential, because the man hasn't missed a beat in jumping essentially from Double-A to the majors. Heyward does everything well, from hitting and hitting for power to running the bases to playing defense to making the correct throws. He could be a once-in-a-generation talent—a Griffey or an A-Rod in the making—or he might have to "settle" for a Miguel Cabrera career path.

Since the break: Heyward has kept the hits coming, going 17-for-39 (.436) to start the second half. Both of his extra-base hits are doubles.

DH—Gaby Sanchez, 26, Marlins

Sanchez lost out to Jorge Cantu in a wide-open competition for the first-base gig prior to the ’09 season. He hit well in Triple-A, but a pair of minor knee injuries limited him to 85 games, and when the Marlins summoned Sanchez to Miami at the end of July, he served almost exclusively as a pinch-hitter. He has been a perfect fit as the club's No. 2 hitter because of his keen plate discipline and line-drive stroke. Good for 15-17 home runs in his best seasons in the minors, Sanchez ought to be good for 20 in the big leagues from time to time.

Since the break: Sanchez has ripped 12 hits in 37 at-bats (.324), among them two home runs and three doubles.

ROTATION ROOKIES
Starting Pitchers

SP—Jhoulys Chacin, 22, Rockies

The return of Jorge de la Rosa from injury pushed Chacin out of the rotation, where he went 5-7, 3.64 in 12 starts. In his first two relief outings, he got rocked for six runs on seven hits over 4 1/3 innings. Chacin has been especially effective away from Coors Field, compiling a 2.57 ERA and 51-to-22 strikeout-to-walk ratio over 42 innings.

Since the break: After making 12 first-half starts, the Rockies shifted Chacin to the bullpen in early July. In four second-half appearances, he's worked 5 1/3 innings, allowing two runs on three hits (3.38 ERA) and taking a loss. He's struck out nine and walked three.

SP—Jaime Garcia, 23, Cardinals

Injuries have cut into Garcia's minor league development (he had Tommy John surgery in ’08), but few pitchers were better during this season's first two months. Through his first 10 starts, Garcia went 5-2, 1.32 while compiling a 51-to-27 strikeout-to-walk ratio over 61 1/3 innings. With three average-or-better pitches, including a plus sinker and curveball, he has easy mid-rotation potential, and he's gotten back on track in July.

Since the break: Garcia has gone 1-0, 2.61 in two starts, recording 10 strikeouts and three walks over 10 1/3 innings.

SP—Mike Leake, 22, Reds

The Reds ushered Leake from Arizona State to the Arizona Fall League to Cincinnati, with no minor league stopover in between. The club remains in the thick of the NL Central race thanks in part to Leake's quality rotation work. He pitches deep into games with nary a wasted pitch because efficiency is the name of the game. What Leake lacks in big-time velocity—he's more effective at 88-91 mph with sink—he makes up for with excellent secondary stuff, including a slider, curve and changeup. And oh-by-the-way, he's 15-for-41 at the plate.

Since the break: He's recorded two groundouts for every flyout while going 1-1, 3.97 in two starts. He's struck out six, walked four and allowed a pair of home runs.

SP—Jon Niese, 23, Mets

No one will confuse Niese with a future ace, but with four average-or-better pitches he's been a steady contributor all season. The lefty (along with knuckleballer R.A. Dickey) has helped ease the Mets' frustration of getting nothing from John Maine or Oliver Perez. Niese goes to his excellent curveball for strikeouts, but he's made progress with his fastball, cutter and changeup, too.

Since the break: Niese pitched seven, one-run innings against the Giants and followed that by allowing three runs (on three solo homers) in five innings to the Diamondbacks. Overall he has 10 strikeouts and four walks over 12 innings.

SP—Stephen Strasburg, 21, Nationals

"Nothing needs to be said that hasn't already been said," a pro scout with an NL organization said. Explosive mid- to high-90s fastball, devastating power curve and an underrated changeup—it's all there.

Roger Clemens, Don Sutton, Mark Prior, Zack Greinke, Dwight Gooden and Felix Hernandez. Those are the pitchers, since World War II, who as rookies have come anywhere close to matching Strasburg's 5-to-1 strikeout-to-walk ratio at his age (or younger). Remarkably, Gooden and Hernandez were 19, while Greinke was 20.

Since the break: More of the same for Strasburg: 14 strikeouts, four walks, no home runs in 11 2/3 innings. He gave up three runs to the Reds in his last start but even so he's 2-0, 2.31 since the break.

BULLPEN ROOKIES
Relief Pitchers

RP—Neftali Feliz, 22, Rangers

The Rangers rank third in the AL with a staff ERA of 3.84. It's the key reason for their 58-41 record and first-place showing in the AL West. And Feliz has been integral to the equation, securing the final three outs of a Rangers win 23 out of 25 times in the first half.

"He’s pretty consistently come out and pitched with an upper-90s fastball, exploding fastball," a pro scout for an AL organization said. "He throws strikes, and has been resilient bouncing back on a closer’s workload for the first time. His curveball is still developing and mostly just a show pitch, which he needs to use. And he’s got the good changeup in there, but doesn’t go away from the fastball often."

Since the break: Feliz has collected five saves in six outings, fanning five and walking none in 5 2/3 innings. He has allowed two runs on four hits (one homer) for a 3.18 ERA.

RP—Jonny Venters, 25, Braves

Just like the Rangers, the Braves have ridden a balanced attack to one of the NL's best records. Venters, who fought his control in the minors, has been crucial to Atlanta's success. A lefty with a live 91-94 mph fastball to both corners of the plate and a sharp slider, Venters shows no platoon split, making him a reliable seventh- or eighth-inning weapon. He's actually been tougher on righthanded batters thus far, limiting them to a .467 OPS, compared with .553 to lefties.

"He's got a quick arm and is having a great year," a pro scout for an NL organization said. "He's a quality arm out of the pen who has helped them get to where they are this year."

Since the break: Venters has opened the second half with 6 1/3 shutout innings. He's allowed four hits while striking out five and walking two.

RP—Ryan Webb, 24, Padres

In the past, Webb's scouting report read much easier than his stat sheet. How could a pitcher with mid-90s heat, a power breaking ball and a decent changeup have such pedestrian strikeout rates? Working almost exclusively out of the bullpen in Triple-A, Webb managed an ordinary 7.5 whiffs per nine innings. But since getting the call to San Diego at the beginning of May, he's gradually gained the Padres' trust, ascending to a seventh-inning role.

Since the break: Webb has opened the second half in poor form, allowing six runs on eight hits in four innings. He sports a 2-to-4 strikeout-to-walk ratio.