By Eriq Gardner //
Let’s talk about coin flips for a moment.
Imagine you have 100 coins in your hand and you dropped them on the ground. Let’s say 50 turned up “heads.” Now imagine you took those 50 coins that landed “heads” and dropped them again. Let’s say 25 turned up “heads” a second time. Now imagine dropping those 25. Let’s say 13 landed “heads.” Now image dropping those 13. Let’s say six coins landed “heads” a fourth time.
Imagine looking at those six coins. Do you think you’d see any unusual properties that would make them prone to landing on “heads”?
Of course not.
But when it comes to evaluating ballplayers, we tend to endow them with similar unusual properties.
Take Dan Haren, for example.
As everyone knows, he’s “prone” to having bad second halves of the season. In his career, he’s got a 3.29 ERA before the All-Star Break and a 4.27 ERA afterwards. On this blog, Eno Sarris already covered
how Haren’s peripheral stats in the second half aren’t to be feared. What will be overlooked by most is that Haren has always been a great first-half pitcher, yet didn’t live up to his reputation this year.
Do first-half/second-half splits mean anything? One regression study couldn’t find
any predictive value in those splits.
In other words, Haren could very well be just like those coins that landed “heads” again and again and again and again. In a large population, a small percentage will exhibit unusual behavior.
For this reason, it’s not worthwhile to buy Haren’s teammate, Adam LaRoche, as a player sure to turn it on now. LaRoche has always been phenomenal throughout his career in the later stages of the season. His career OPS before the All Star Break? .776. His career OPS after the All Star Break? .905.
It doesn’t matter.
If you flipped those six coins above that landed “heads” four times straight, maybe three would land “hands” a fifth time. But that also means three would land “tails.” A 50/50 proposition. That’s what you’re getting in betting that LaRoche will be a 900+OPS player from here on out.
Let’s move onto another Arizona Diamondback, Chad Qualls. Some might look at Qualls and see a great few months coming. He’s currently showing a 8.35 ERA, belying a 3.64 xFIP.
Might he be even better than that, due some great luck from all the horrible luck he’s had so far? Perhaps Qualls can get his closer gig back and become the best relief pitcher in baseball.
Back to the coins. Imagine those three special coins that landed “heads” five times straight. Are they due for “tails”? Nope. Still a 50/50 proposition.
Betting that Qualls will outperform his underlying skills is the same as betting that those coins will turn up “tails.” Betting that Qualls is cursed is the same as betting those coins will turn up “heads.” Smart fantasy managing means not betting on hot streaks. It means finding a midpoint, and really reserving judgment on which way that coin will land.