Worth remembering are some parallels with our Sox. Both teams, the Boston Red Sox and the Philadelphia Athletics, helped found the AL in 1901 and both had early success. The A's won 6 pennants and 3 WS by 1914 under the leadership of Connie Mack--and later WS in 1929 and 1930 despite the NYY.
Ultimately, however, a 30 year decline leading almost to bankruptcy drove the A's move to KC in 1955 and on to Oakland in 1968, where they quickly won three straight WS (1972-74) under owner Finley and another, their most recent, in 1989 under Hass, whose A's had the highest payroll in MLB and went to three straight WS (1988-90).
New owners in 1995 slashed payroll, however, because of low attendance and also began looking at sabermetrics to get more value from players. Beane began as an A's scout in 1990 and by 1997 had become the new GM and continued to pursue low cost, but useful players using sabermetrics. In 2002 he turned down new Sox owner John Henry's 2002 offer of a $12.5M salary to move to Boston, which by then had endured an 84 year WS drought.
As we all know, John Henry has used a two-pronged approach--both sabermetrics and high salaries--to enable the Sox to break the drought in 2004 and win 3 more WS in 2007, 2013, and 2018, making the Sox the most successful MLB team since 2003.
Two years ago John Henry hired the newest version of Billy Beane away from the also-competitive-while-paying-low-salaries Tampa Bay Rays--Chaim Bloom. He did this because that last WS win in 2018, while exhilarating, was also costly because DD's forte is buying talent, especially pitchers.
So this year both teams are winning because of astute acquisitions and skilled on field management.
To a degree. The Sox are still paying a lot more for players, the residue of Dombrowski's free rein on spending, which was somewhat ameliorated in 2019-2020 by the departures of 2018 players Mookie Betts, David Price, Rick Porcello, JBJ, Beni, Hanley Ramirez, Sandoval, Pedroia, Kimbrel, Pomeranz, Moreland, Nunez, Kelly, and Holt. The Sox are still paying some or all of Price, Beni, and of course Pedey--a total of $31M, over half of all the A's salaries ($58M) this year. The A's highest paid player is Andrus at $8.3M. The Sox are paying Sale (yet to pitch) $20M, Bogey $20M, JDM $19M, Eovaldi $17M, Richards $8.5M(!!), ERod $8.3M (!!), and Ottavino $8.1M. In that context Devers is a humoungous bargain at $4.8M