How Well Do Our Playoff Odds Work?
It’s the time of year when folks doubt the playoff odds. With the St. Louis Cardinals going from 71-69 long-shots to postseason clinchers, and the rollercoaster that is the American League Wild Card race, you’ve probably heard the skeptics’ refrains. “You had the Jays at 5%, and now you have them at 50%. Why did you hate them so much?” Or, hey, this tongue-in-cheek interview response that mainly makes me happy Adam Wainwright reads our site:
Adam Wainwright: “FanGraphs had us at like a negative 400 percent chance to make the playoffs, and we just proved everyone wrong. We're going to try to and keep doing that.”
— Zach Silver (@zachsilver) September 29, 2021
In that generic statement’s defense, it really does feel that way. In your head, 5% rounds to impossible. When the odds say “impossible” and then the season progresses to a point where outcomes are far less certain, what other impression can you take away than “these odds were wrong”?
I feel the same way from time to time. Just this year, the Cardinals and Blue Jays have been written off and then exploded back into contention. St. Louis bottomed out at 1.3% odds to make the playoffs – in August! It’s not quite negative 400 percent, but it sure feels that way. Can it really be that those odds were accurate, and that we just witnessed a one-in-100 event?
To investigate this question, I did what I often do when I don’t know where to turn: I bothered Sean Dolinar. More specifically, I got a copy of our playoff odds on every day since 2014, the first year when we calculated them using our current method. I left out 2021, as we don’t have a full season of data to use yet, but that still left me with a robust (some would say too robust) amount of data. Read the rest of this entry »