Did the A's invent on-base analysis?

No. Bill James and the sabermetrics community had argued for decades that on-base percentage was undervalued. Oakland's innovation was institutional: it was the first front office to bet its actual roster construction on the research while the rest of the market still priced players the old way.

Did Moneyball win a championship?

No. The 2002 team won its division and lost a short playoff series, and the front office itself argued that short series are near coin flips that no valuation model can control. The method's proof was regular-season wins per dollar, not October outcomes.

Does the on-base edge still exist?

Not as an edge. Once rival clubs hired analysts and repriced the skill, on-base ability began costing what it is worth, and the advantage competed away. Modern front offices hunt newer mispricings, which is the strategy's real, durable lesson.

sports · 2002

Moneyball and the Mispriced Player

The 2002 Oakland Athletics beat a market, not just other teams: they bought wins the rich clubs did not know they were selling, until a bestseller told everyone the price.

Facts drawn from league statistical records and contemporary reporting; payroll tallies vary by accounting method and are labeled accordingly.

The 2002 Oakland Athletics carried a payroll of about 41 million dollars while the New York Yankees spent about 126 million dollars, roughly three times as much [MODELED]. Both clubs won 103 games that season [VERIFIED]. That equivalence, purchased at a threefold discount, is the whole story in one line, and general manager Billy Beane's method for achieving it became the defining case of market inefficiency in professional sports.

The method was to trust measurements over impressions. Baseball's talent market priced players heavily on visible athletic tools and scouting projection, while underpricing the unglamorous skill most tightly linked to scoring runs: getting on base. Oakland bought on-base ability wherever it came cheap, in slow catchers, injured pitchers, and castoff first basemen, and after losing star Jason Giambi to a contract it could not approach, the front office famously replaced his on-base contribution in aggregate across several inexpensive players rather than attempting to replace the man.

Sources

[VERIFIED] The 2002 Oakland Athletics' record, season results, and the winning streak Baseball-Reference, 2002 Oakland Athletics season page
[VERIFIED] The 2002 New York Yankees' record and season results Baseball-Reference, 2002 New York Yankees season page
[VERIFIED] The 20-game streak's place among the longest winning streaks in league history MLB.com, review of the longest winning streaks in MLB history
[MODELED] The narrative account of the A's method and its publication history Michael Lewis, Moneyball: The Art of Winning an Unfair Game, W. W. Norton, 2003 (secondary narrative source)