One thing that's bizarre about baseball is the unequal number of teams in each division. In the AL West, you have a 25 percent chance of making the playoffs, all other things being equal, while in the four five-team divisions you have a 20 percent chance, and in the NL Central you have a 16.7 percent chance.
But that's assuming all things are equal, and they're plainly not. Compounding the problem is market size, and with it payroll. So if you're in the NL Central and have a small payroll, e.g., the Pirates, you're behind the eight ball on two fronts. Conversely if you're in the AL West and have a big payroll, e.g., the Angels, you've got two massive advantages right off the bat.
I'd also posit (and I haven't studied or proven this) that playing in a pitcher's park is another advantage. My theory - besides seeing that teams like the Marlins and A's often do more with less - is that baseball's 162-game endurance test hits pitchers the hardest. They're most likely to get hurt, and reducing their workload is important. In parks where there's more foul ground, or more would-be off-the-wall shots and home runs become flyouts, pitchers throw less pitches, and preserve their arms.
So the Angels are the only team in the four-team West with a payroll over $100 million and that occupies a pitcher's park. Incidentally, Anaheim has only $15 million more in payroll than the Mariners this year, but Seattle's still recovering from the Bill Bavasi era which was almost Isiah Thomas-like.
Billy Beane's genius levels the playing field a bit, but in the last half decade the Angels have made the postseason every year but one - (four division titles, one second place). That the Angels haven't made a World Series in that time doesn't mean much to me - the Phillies last year or the Cardinals in 2006 show that most teams that get into the postseason can get hot for a few weeks.