Examining four playoff coordinators

— -- We all do it, if we're being honest.

With the passage of each decade, each time our ages have a zero on the end -- or even begin to creep closer to it -- we take stock.

Where are we? What have we done? Where are we going? Are we where we want to be?

Often, it's a simultaneously rewarding and harrowing exercise. Even in the celebration of accomplishment, there's recognition that the climb is never complete. The mountain continues to rise, and rise, in front of us.

With that in mind, the magic number for the upcoming College Football Playoff is 39.

That's the age of four of the coordinators coaching in the semifinals: Alabama's Lane Kiffin and Kirby Smart, Oregon's Scott Frost and Ohio State's Tom Herman.

Kiffin, Smart, Frost and Herman will turn the Big 4-0 in 2015, and each man finds himself in a different phase of the wild, weird coaching life.

Their varied career stages illustrate hiring trends and the fact that most coordinators, including these four, have thought often of becoming a head coach.

One has already experienced it. And failed.

Kiffin

Clearly, Kiffin has a different perspective than the others, already having been a head coach in the NFL, the SEC and at his "dream job" -- USC.