Mike Shanahan's Broncos never made the playoffs with Jay Cutler as the starting quarterback. (Getty Images)

By Don Banks, SI.com

I guess even Teflon has an expiration date. As recently as Monday I had marveled how nothing ever seems to stick to Denver head coach Mike Shanahan, despite his team’s glaring failures in recent seasons.

But even Shanahan, the second longest tenured head coach in the NFL, couldn’t avoid accountability for the Broncos’ latest collapse. His back-to-back Super Bowl wins in Denver now 10 years old and providing him cover no longer, the Broncos made the surprise move of the NFL firing season so far by dismissing Shanahan on Tuesday afternoon.

It was not without cause. There was this year’s historic squandering of a three-game AFC West lead with three games to play, and much more. The Broncos haven’t made the playoffs the past three seasons, and own just one postseason win in the 10 years since quarterback John Elway retired (a 2005 AFC Divisional round defeat of New England).

In the past four seasons alone, Denver wasted a shot at the Super Bowl by losing at home in the AFC Championship Game to the underdog and sixth-seeded Steelers in 2005, lost in Week 17 at home against a sub-.500 49ers team to blow a trip to the 2006 playoffs, and this year somehow managed to avoid the playoffs despite holding a three-game lead over second-place San Diego with three weeks to go.

Nine winning seasons, seven playoff berths and three conference championships in 14 years certainly sounds impressive, but the reality is that Shanahan never remotely approached the same level of success with any of the other quarterbacks who followed Elway after their four-year stint together.

Not Brian Griese, who the Broncos lavished with a huge contract and then parted ways with shortly thereafter. Not the erratic Jake Plummer, who Shanahan acquired from Arizona and then gave up on following his AFC title game loss to Pittsburgh. And not Jay Cutler, the current Denver quarterback and 2006 first-round pick who has both tantalized and tormented the longtime Broncos coach with his own inconsistent ways.

For most of the past 10 years, the Broncos have been NFL enigmas, capable of playing great for short spurts of almost every season, but never again finding the personnel combination and chemistry that served to bring them their only two NFL championships in 1997-98. And the blame for that has finally landed on the shoulders of Shanahan, who has always been pretty much a one-man show in Denver, calling almost every shot.

This time, the defeats finally caught up to him. In the NFL, no one is Teflon forever.