In a season of great divisional and wild-card races, last year’s NL West scramble may have been the best of the bunch. The Dodgers, Padres, and Diamondbacks all spent at least six weeks in first place, and by the end, just one full game separated the top three teams in the standings after the Rockies beat the Padres in a Game 163 playoff to decide the wild-card. The West looks similarly wild this year, as Baseball Prospectus’s PECOTA projection system forecasts the Dodgers, Diamondbacks, and Rockies to finish with 87, 87, and 82 wins, respectively, the tightest three-team cluster in any division. As with last year, the outcome may well rest on the shoulders of young, homegrown talent. The Dodgers, Diamondbacks, and Rockies have earned reputations as three of the game’s top player development machines, offering a pipeline of top prospects to combat the ever-rising cost of signing free agents – especially important for the small-market Rockies and Diamondbacks. All three are poised to augment their lineups and pitching staffs with even more prized prospects as the year goes on.

Hardly anyone predicted the Rockies could win the NL pennant last year, and nobody foresaw their season-ending 14–1 dash. However, BP prospect guru Kevin Goldstein ranked the Rockies’ minor-league system the game’s second-best at the outset of the season, noting their ability to provide instant help in the form of 22-year-old shortstop Troy Tulowitzki, who hit .291 AVG/.359 OBP/.479 SLG with 24 home runs while anchoring the league’s best defense. The system also produced a pair of hard-throwing hurlers — 23-year-old right-hander Ubaldo Jimenez and 21-year-old lefty Franklin Morales – who patched a rotation wracked by injuries in time for their amazing stretch run. Meanwhile, 24-year-old Manny Corpas, a second-year reliever, took over the closer role from Brian Fuentes by midyear, saving 19 games after July 6.

Strong player development is hardly a new thing for the Rockies; it’s arguably the only area in which the team (once notorious for a $172 million binge on free-agent busts Mike Hampton and Denny Neagle) has ever excelled. Their 2008 Opening Day lineup featured seven homegrown players, including five-time All-Star Todd Helton, 2007 MVP runner-up Matt Holliday, and former first-round draft picks Tulowitzki (2006), Jeff Francis (2002), and Jayson Nix (2001). Three days later, with Chris Iannetta behind the plate, and Ryan Spilborghs in center field, they featured an all-homegrown nine. Nix, 25, is a late-arriving, good-field/no-hit rookie; PECOTA forecasts him for a .245/.300/.379 showing but defense at second base that’s nine runs above average. Iannetta, also 25, was expected to win the starting catcher job last year, but a .158 AVG in April coupled with a solid performance from Yorvit Torrealba consigned him to the backup backstop role. Still, Iannetta forecasts as the better hitter, and he may yet claim the job.

The Diamondbacks won the division with six homegrown regulars last year, doing so despite uneven performances from their most highly touted youngsters. Shortstop Stephen Drew had starred in a late-2006 call-up but slumped to .238/.313/.370 in his first full season. Center fielder Chris Young slugged 32 homers and stole 27 bases, but hit just .237/.295/.467. Key help came from early-season call-up Mark Reynolds, who subbed at third base for injured Chad Tracy and walloped 17 homers.

But the August promotion of 19-year-old right fielder Justin Upton (brother of Tampa Bay’s B.J.) may have the most significance going forward. The overall first pick of the 2005 draft, Upton climbed the ladder from High-A ball last year, and while he hit only .221/.283/.364 with Arizona, his talent draws comparisons to fellow former no. 1s like Ken Griffey Jr. and Alex Rodriguez. “Upton is a monster,” marveled Goldstein after watching him homer in three straight games against Colorado last weekend.

The Dodgers, meanwhile, own a reputation for scouting and player development unequalled since the days of Branch Rickey 60 years ago. They have the drafting prowess of assistant general manager Logan White to thank for their latest crop. First baseman James Loney, White’s inaugural first-round pick in 2002, is a sweet-swinging 24-year-old lefty who’s a bit short on power but nonetheless the owner of a .323 career batting average through his first 151 games in the majors. Russell Martin, a 2002 17th-rounder, has quickly distinguished himself as the league’s best catcher and the team’s unofficial captain. Right fielder Matt Kemp, 23, is a raw former basketball star plucked in the sixth round of the 2003 draft; he belted seven homers in his first 17 major league games in 2006, then hit .342 after honing his swing in Triple-A early last year. The pitching staff features 23-year-old Chad Billingsley, who went 12-5 with a 3.31 ERA while shifting to the rotation from the bullpen, and 23-year-old, 290-pound setup man Jonathan Broxton a closer-in-waiting with a high-90s fastball.

But, wait … there’s more! Third baseman Andy LaRoche – one of three Dodger hot cornermen currently on the disabled list – will vie with Nomar Garciaparra for the starting job once they both return from injury; the 24-year-old is the team’s top hitting prospect but his efforts to break through have been stymied by injuries. Even more tantalizing is 20-year-old southpaw Clayton Kershaw, a blue-chip pitching prospect. Despite less than 25 innings above A-ball under his belt, he spent most of March in the big-league camp and drew raves for his poise and his arsenal. Though sent to Double-A to start the season, he’s poised for a midsummer promotion, either as the fifth starter or – of particular interest given new manager Joe Torre’s experience last year – in a Joba Chamberlain-esque setup role.

It’s Torre who may draw the most scrutiny of any newcomer in the division. As the Yankee skipper, he often drew criticism for preferring marginal veterans over untested prospects, but his latter-day ability to integrate Robinson Cano, Melky Cabrera, Phil Hughes, and Chamberlain into the mix mitigated that somewhat. Already he’s drawn fire for juggling Kemp with expensive, unproductive Juan Pierre in the outfield, and if Garciaparra and LaRoche are ever healthy at the same time, all eyes will fall on that choice, too. Given a slim margin for error, nothing less than a playoff spot may ride on Torre’s willingness to choose youth over experience.

Mr. Jaffe is a writer for BaseballProspectus.com.