Whether by necessity or by choice, teams work rookies into the starting lineup each year. The Colorado Rockies, for example, have given 39% of their plate appearances to rookies this season, by far the highest percentage in the majors. With no hope of competing in their division, they have the luxury of giving these youngsters extended trials at the highest level, free from the pressure to contribute in a pennant race.

For the Atlanta Braves, there’s no such luxury. They sit four games out of first place in the NL East, which has become the most competitive division in baseball. Just seven games separate the five teams in the standings, and with nine rookies on their major league roster as of Sunday, the Braves have entrusted their run at the division title in large part to players with little big-league experience.

It wasn’t supposed to be this way. Tim Hudson, Mike Hampton, and John Thomson were supposed to anchor the rotation – all are currently on the DL. Veteran outfielders Brian Jordan and Raul Mondesi weren’t supposed to be as abysmal as they’ve been. In the infield, Chipper Jones was supposed to remain healthy and Rafael Furcal was supposed to remain effective.

With no alternatives, the Braves have turned to their prospects for help. Not all of them are ready to contribute, though, and there’s a real chance that the Braves will miss the postseason for the first time since 1990. Here’s a look at where and why the Braves have been forced to rely on their up and comers.

OUTFIELD Mondesi was designated for assignment after hitting .211 AVG/.271 OBA/.359 SLG in 155 plate appearances. To better contextualize that performance, we’ll turn to Value Over Replacement Player (VORP), a Baseball Prospectus metric that measures, in runs, how a player’s offensive production compares to what a readily-available replacement player might have contributed if given the same number of at bats. Mondesi accumulated a VORP of -4.3, meaning his presence in the lineup was more harmful than having a replacement-level player in there. Left fielder Brian Jordan has fared even worse: He’s batted .233/.279/.296 for a -6.9 VORP in 204 at-bats this season.

Mondesi’s job was given to 2000 first round draft pick Kelly Johnson, who has hit .204/.348/.389 in 66 plate appearances. A .276/.358/.449 hitter in the minors, Johnson greatly improved his plate discipline last year at Triple-A Richmond, hitting .310/.438/.581 with a strikeout-to-walk ratio of 34/22. He played in only 44 games at that level, though, so it’s too early to tell whether that line demonstrates a new command of the strike zone.

So far in 2005, Johnson has walked 10 times to only seven strikeouts, a good sign amid his otherwise ugly stat line. Still, Johnson doesn’t have to play particularly well to qualify as an improvement over Mondesi.

Another young outfielder, Ryan Langerhans, made the team out of spring training and has since spent time in all three outfield positions. Langerhans, a 1998 third-round pick, enjoyed a monster season at Richmond in 2004, hitting .298/.397/.518 in just under a full season, which was a marked improvement over his career minor league line of .265/.352/.414.

His performance so far this season is a somewhat disappointing .243/.318/.441 (3.6 VORP). If the Austin Kearns-to-Atlanta rumors prove true, both Johnson and Langerhans will make excellent part-time outfielders should Bobby Cox elect to mix and match.

CATCHER Rookie catchers Brian Mc-Cann and Brayan Pena made their major league debuts last week while normal backup catcher Eddie Perez sat out with an injury and Johnny Estrada recovered from his bone-rattling collision with Darin Erstad. Pena has since been sent back to the minors, but Mc-Cann remains in Atlanta.

McCann has gotten just 16 plate appearances so far, but there’s talk that the Braves may skip the step of letting him hit in the high minors and keep him up with the big club all year despite his defensive shortcomings behind the plate. He’s shown big-time power in the low-minors, and was off to a .265/.359/.476 start at Double-A Mississippi before his emergency call-up.

INFIELD Infielder Pete Orr, 26, was a career .265/.317/.340 hitter in the minors, and is coming off a 2004 season in Richmond in which he hit .320/.349/.404 in 460 at-bats. That .404 slugging percentage is a bit misleading, as he hit one home run, 16 doubles, and 10 triples. Triples, though they increase a player’s slugging percentage, are usually an indicator of speed rather than power. He’s currently hitting .312/.346/.442 (4.1 VORP), which is way out of line with his minor-league career. The history of players who learned to hit in the majors is short; Orr has to continue hitting .300 to have any value as a utility player.

Third baseman Andy Marte was Baseball Prospectus’s no. 1 prospect entering this season. Even at his young age, his game features a startling lack of holes. The only obstacle in Marte’s way was incumbent third baseman Chipper Jones, who didn’t take well to his outfield trial last season. Jones has since gone down with a foot injury, clearing the way for Marte,who has gotten off to a slow start, hitting just .188/.282/.250 in his first 38 plate appearances, good for a VORP of -2.5.He’s a legitimate star in the making, though, and it’ll be interesting to see what the Braves do when Jones returns, likely later this season.

Another in the Braves’ seemingly endless line of quality position prospects, Wilson Betemit was once referred to as the Braves’ third baseman of the future until Marte showed up; now he’s the Braves’ jack-of-many-trades, playing multiple infield positions and compiling a VORP of 9.1 in 88 at-bats – a far sight better than Furcal, who has limped to a .221/.274/.346 start (VORP of 4.2).

PITCHERS With three-fifths of their rotation currently on the DL and off-season acquisition Danny Kolb an unmitigated disaster in the bullpen thus far, the Braves have had to rely on more than a few rookie pitchers. The most successful of these – and the most likely to succeed going forward – is Kyle Davies, who has made seven starts in 2005.

In 426 minor-league innings, Davies was a bit wild, walking 3.08 men per nine innings. His major league debut has been a bit worse than that, at 4.9/9 IP. But his VORP of 8.1 suggests that he’s done little to hurt his team while auditioning for his future job. Though his control issues might need to be resolved in the minors, his minor-league K/9 rate of 9.44, coupled with a .51 HR/9 rate, indicate his potential as a significant addition to the rotation.

Some of these rookies, like Marte, Johnson, and Davies, fit into the organization’s long-term plans and represent tomorrow’s stars. Some, like Orr, are simply short-term placeholders, responsible for keeping the Braves afloat in the tight NL East race before Chipper Jones, Mike Hampton, and Tim Hudson return from their DL stints.

Most of these players will spend this season working through growing pains; some, like McCann, have been prematurely thrown into the spotlight. Still, the Braves’ organizational depth has provided them with better players than the reserves on other teams with injury problems (the Giants and Yankees, to name two).While stat heads might balk at their scout-heavy drafts, they’ve been enormously successful implementing their philosophy. That gives this team a shot at hanging around, and at least an outside shot of defying the skeptics yet again.

Mr. Erhardt is a writer for Baseball Prospectus. For more state-of-the-art commentary and information, visit baseballprospectus.com.