There are teams that have been "lucky" to get to Omaha. There have been teams that have been "lucky" to win it all even (Oregon State last year, as they almost didn't even make it in the field of 64). You have to at least be good enough to be able to get the breaks, but in a 9 inning game, a 3 game series, or a double elimination regional, the best team doesn't win every time.
I know you guys hate hearing it, but that's what Polk means when he says "that's baseball". And he's right to an extent. In a single game, a single weekend, or any other small cross section of games, anything can happen.
What you can't fake is being good over a full season. Vanderbilt last year was one of the Top 5 teams in the country, maybe the best overall, but they had a couple off nights, and Michigan kept them from advancing. Michigan was not a better team than Vandy, and Vandy probably would've won that regional 9 times out of 10, but they had an off weekend and went home early.
South Carolina had a team a few years back that dominated the SEC and lost something like 6 or 7 games the entire season. They were clearly the best team in the country that year, but they lost to Clemson in the 3 game national championship series. Clemson was not a better team than South Carolina, but they played better than them for 1 weekend and won the national title. Point being, again anything can happen in a short series.
In basketball, George Mason made the Final Four a few years back. Were they one of the Top 4 teams in the country? Definitely not, but they played well enough and got the breaks at the right time to make a run.