It didn’t take genius to foresee the collapse of the World Champion Cardinals. With a poorly-executed off-season plan and a nearlybarren farm system, general manager Walt Jocketty did little to upgrade a club that limped into last year’s playoffs with an 83–78 record before their unlikely title run. With ace Chris Carpenter sidelined by bone spurs in his elbow since Opening Day, plus sluggers Albert Pujols, Jim Edmonds, and Scott Rolen all off to slow starts, it’s been clear for weeks that a repeat performance just isn’t in the Cards.

Filling the power vacuum in the NL Central so far have been the upstart Brewers. Storming out to a 24–10 record behind the potent 1-2 punch of first baseman Prince Fielder and shortstop J.J. Hardy, the Brewers opened up a 6.5-game lead on the retooled Cubs before the latter’s irascible new manager, Lou Piniella, had earned his first ejection. Even when gravity brought the Brewers back to earth — they lost 19 of their next 28 games — neither the Cubs nor any other Central team seized the initiative; Milwaukee’s lead never dwindled below 4.5 games.

That lead is back up to seven games, and if you were in the vicinity of Miller Park Monday night, you may have heard the window of opportunity slam shut on the rest of the division. Yovani Gallardo, considered one of the top 20 prospects in the minors by both Baseball Prospectus and Baseball America, put together an impressive major league debut, limiting the Giants to four hits and three runs over 6.1 innings. Rickie Weeks doubled twice in his return from the disabled list, and Fielder socked his NL-best 26th homer to give the Brewers their sixth win in eight games.

This is unfamiliar territory for the Brewers, who haven’t finished above .500 since 1992. The incompetence that characterized the last decade or more of Selig family mismanagement — at best, they starved the team into the cellar to justify daddy’s, ahem, the commissioner’s points about market-size inequities — is a thing of the past. Since the hiring of Doug Melvin as general manager in 2003, things have only gone up. A more enlightened owner, Mark Attanasio, purchased the club in 2004, and the Brewers have emphasized player development as their avenue to competition while staying away from the mid-market mediocrities that can bloat a payroll without adding wins. Gallardo, Weeks, and Fielder are all products of the system, as are shortstop Hardy, third baseman Ryan Braun; the starting outfield of Geoff Jenkins, Bill Hall, and Corey Hart, and staff ace Ben Sheets.

All are contributing to the club’s success. Hardy was limited by injuries to just 159 games over his first two seasons, but has surprised with 17 homers. Braun is hitting .295 AVG/.333 OBA/.523 SLG since taking over for the anemic Tony Graffanino/Craig Counsell platoon last month. Hart has hit a searing .345/.433/.707 from the leadoff spot while Weeks was sidelined by wrist trouble. Sheets has bounced back from shoulder woes to lead the staff with a 3.31 ERA. Gallardo showed enough poise and command of his arsenal that he may force a rotation shuffle once injured no. 2 starter Chris Capuano returns.

Fielder has been the most impressive of all the Brewers. The son of former AL slugger Cecil Fielder was hitting balls out of Tiger Stadium as a teenager, and while he’s battled weight issues that at times pushed him above 300 pounds, he’s surprisingly nimble afoot. More important, he’s the team’s most productive hitter, ranking sixth in the league in Value Over Replacement Player (VORP), the number of runs beyond the level that a reserve or freely available minor leaguer would theoretically produce.

Contrast the Brewers’ plan to that of the Cubs, who lavished over $285 million in contracts for Alfonso Soriano, Aramis Ramirez, Ted Lilly, Jason Marquis, and Mark DeRosa this past winter. They actually have the division’s best run differential at plus-21 (the Brewers are at plus-12), but at 31–37, they’re mired under .500 with the other alsorans in the division thanks to a 6-14 record in one-run games. Evidence of their frustration is everywhere; thus far this month, catcher Michael Barrett sparred with pitchers Carlos Zambrano and Rich Hill, Piniella drew and served a four-game suspension for kicking dirt on an umpire, Lilly was ejected for hitting a batter 10 pitches into a start, and first baseman Derrek Lee received a five-game suspension for sparring with the Padre Chris Young after being hit by a pitch.

At least the Cubs have a pulse and a plan. Neither has been evident in the Cardinals. Faced with the freeagency departures of two pitchers instrumental in their playoff run, Jeff Suppan (the NL Championship Series MVP signed with the Brewers) and Jeff Weaver (who after pitching the Series clincher signed with Seattle), the team spent just $4 million to ink Kip Wells while electing to convert relievers Adam Wainwright and Braden Looper to starting roles. Wells has gone 2–11 with a 6.93 ERA, which qualifies as an unmitigated disaster. Wainwright and Looper have put up ERAs about a half-run worse than the league average. Series hero Anthony Reyes, the closest thing to a prospect in the system, went 0–8 with a 6.34 ERA before being demoted. Poor substitutes for Carpenter all around; as St. Louis Post-Dispatch columnist Bernie Miklasz wrote recently, “This is probably the worst starting rotation in more than 100 years of Cardinals baseball.”

Not helping matters is the injury-riddled offense, 24th in the majors in scoring at 4.3 runs a game. Edmonds underwent offseason shoulder and foot surgeries, and hasn’t been 100 percent all year. Hitting just .238/.308/.394, he was placed on the DL this week, joining Carpenter, Looper, shortstop David Eckstein (back), catcher Yadier Molina (broken wrist), and outfielder Preston Wilson (knee) on the sidelines. Rolen is slugging just .386. Second baseman Adam Kennedy, Jocketty’s other “big ticket” signing (three years, $10 million) ranks among the league’s least productive hitters, with a -9.4 VORP off .211/.281/.263 hitting.

Seldom has a World Champion fallen on hard times so quickly. Yet, one team’s demise is another team’s opportunity. With a talented young nucleus, a smart front office, and a fully developed plan, the Brewers were well-positioned to take advantage of the Cardinals’ struggles. Don’t be surprised if they maintain their spot atop the NL Central.

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