I think this is exactly it. This team keeps proving year after year that they're not dependent on any individual. They lost Derek Johnson, they were fine. They lost David Stearns, they were fine. They lost Craig Counsell, they were fine.
If anything, I think you need to go back to the sale of the team to Mark Attanasio to find a common thread for the success they've had over the past 15ish years. He's created a culture in this organization that didn't exist for a looooong time before he took the reigns. They've had some ups and downs during his ownership, but there has been a whole lot more hope and fun engrained in the team throughout his ownership than existed (or more accurately, didn't exist at all) throughout the 90's and early 2000's. I know there are a lot of people that aren't fans of MA, but he seems to have done a great job filling the front office and coaching staffs with very smart people that have created the successful organization they have today and I'm certainly happy to have him on board!
Addendum:
Just for a little more perspective, I did a comparison of the "Bud Selig Era (1970-1992)", the "Wendy Selig-Prieb Era (1993-2004)" and the "Mark Attanasio Era (2005-present)":
1970-1992: 1791 W, 1870 L (.489 W%, 19th best in MLB), 11 seasons .500 or better, 2 division titles (plus two 2nd place finishes), 2 playoff appearances (including a World Series appearance)
1993-2004: 825 W, 1051 L (.440 W%, worst in MLB), 0 seasons .500 or better, 0 division titles (highest finish: 3rd place), 0 playoff appearances
2005-present: 1575 W, 1470 L (.517 W%, 8th best in MLB), 12 seasons .500 or better, 4 division titles (plus five 2nd place finishes), 7 playoff appearances (including two NLCS appearances)
Life has been much better since Mark took over :)