What’s the half-life of a pitching ace?

We have this weird tendency to think things will last forever. When they don’€™t, we tend to become frightened and defensive. If you really want to have a more positive outlook on your life, a tremendous first or second step is embracing uncertainty, rather than fearing and resisting it.

As sports fans, we tend to assume that the great players of today will be the great players of tomorrow. Actually, that’s nearly always true in a literal sense. Mike Trout will be great tomorrow. The day after tomorrow, too.

But man, there’s just so much uncertainty. When I was a boy, I assumed that George Brett would win the batting title just about every year. Well, he won three batting titles in his career. When Brett batted .390 and was Most Valuable Player in 1980, I assumed he would win a few more awards; after all, he was only 27 that season. Well, he would play for another 13 seasons, and finished in the top 10 in MVP balloting just twice more. And Brett’s a Hall of Famer!

Pitchers are even less predictable than hitters. We tend to think of young pitchers as being particularly unpredictable, because of the injury risk. And I believe that’s true. But it’s not like we know what the veterans will do, either.

This point is driven home in Neil Weinberg’s recent Beyond the Box Score piece, in which he measures the “lifespan” of a pitching ace. In a nutshell, Weinberg simply defines an ace – basically, 20 percent better than average over the course of three seasons – and checks to see how many maintain that status in the following seasons.

Quick answer? Not many. Weinberg:

I grabbed five years of data, which includes just three seasons in which we can evaluate his claim. Yet despite limited data collection and absolutely no effort to align myself with his prior expectations, 14 of 30 pitchers classified as aces in 2010-2012 were aces two years later …

Certainly this method institutes an arbitrary cutoff and obviously can’t perfectly capture injuries. Wainwright’s Tommy John happens right in the middle, but he’s back to being an ace. Greinke fell off the list, but he’s close. Verlander is still on the list because he was so good in the early part of the cycle. Haren, Wilson, Sabathia, Halladay, Lincecum, Jimenez, and (maybe) Lester are off for good. Verlander probably will be shortly.

Some aces last, but most don’t.

In 1985, I assumed that Bret Saberhagen would be an ace forever. Or at least until he was 45 or 50 years old. Saberhagen’s tenure as an ace – by Weinberg’s definition, anyway – ended well before he turned 30, because he just couldn’t stay healthy with any consistency at all. Saberhagen was one of the many dozens or maybe hundreds of pitchers who demonstrated Hall of Fame talent for a few seasons but just couldn’t handle the rigors of throwing 200-some innings per season.

Just for fun, I thought I’d check five old-time seasons. My definition of “ace” isn’t the same as Weinberg’s. I’m just looking at top five WAR guys in each season, according to FanGraphs. See how many Hall of Famers you spot!

1954: Robin Roberts, Mike Garcia, Harvey Haddix, Virgil Trucks, Bob Rush

1964: Don Drysdale, Bob Veale, Juan Marichal, Dean Chance, Larry Jackson

1974: Bert Blyleven, Fergie Jenkins, Jon Matlack, Phil Niekro, Steve Busby

1984: Dwight Gooden, Rick Sutcliffe, Dave Stieb, Mike Witt, Fernando Valenzuela

1994: Greg Maddux, Randy Johnson, Bret Saberhagen, Jack McDowell, Roger Clemens

2004: Randy Johnson, Ben Sheets, Johan Santana, Curt Schilling, Jason Schmidt

So that’s 29 pitchers and eight Hall of Famers, plus three more consistently tremendous pitchers in Clemens, Stieb, and Schilling.

I think no matter how you study this issue, you’re going to reach the same conclusion: Only about half the great pitchers today will be great tomorrow, let alone next week.

You know. Figuratively speaking.