Yup, defense is where it is at. The SF Giants won two WS in 3 years by (accidentally, I think) putting together a team that was focused on pitching and defense while everyone else was focused on offense.
While offense is WAY more important, it is too well understood now to gain any advantage over other teams. In 2002, Billy Beane could flip a guy with a great swing or subjectively good defense for someone with better OPS+ and generate wins because everyone else valued the scout's opinions and not the numbers. In 2014, everyone values OPS+/PECOTA/Cairo over subjective opinion so the market has become almost completely efficient in that regard.
The 2010 and 2012 SF Giants had above average (but not spectacular, particularly in 2012) pitching and absolutely awful hitting but managed to win 2 championships when the current state of research says that they shouldn't. One, you could explain it away as a fluke. Two? Maybe there's something there and defense would seem to be where the current blindspot is and if someone can get ahead of the crowd in understanding it, they can get ahead of the crowd and intentionally put together a championship team in that way.