There is an excellent column by writer Bruce Jenkins in today's SF Chronicle.
Jenkins makes a valid point on how relatively small market teams like the A's and Giants can be competitive without overspending or mortgaging their futures.
He calls it "baseball intelligence." We have commented in the past on player's having a "baseball IQ." i.e. inherently knowing what to do in a given situation and/or anticipating the situation to make the appropriate play. Players will raw talent and skills may still lack the baseball field intelligence to utility those skills to their maximum potential.
Jenkins takes that requirement to the front office. Some teams have more organizational "baseball intelligence" than other teams. He states that "the game's most essential truths: that scouting, character and
basic instincts are the tools that build a winner."
Both teams have built winners. The Giants rely upon scouting and field observations more than computer sabermetrics to build their roster. The A's pioneered the mathematical approach to player evaluations. Both systems can work.