November 7, 2013
Rereading Nate Silver: 4. Pitcher Breakouts
In which Nate introduces us to his projection system's attitude toward pitchers, undoubtedly surprising many at the time if not our more modern audience.
Abstract: Nate repeats his exercise from a week earlier, using PECOTA to go over Peter Gammons’ industry-sourced “breakout” list, this time with pitchers. PECOTA, and Nate, are predictably cautious, noting that nearly every breakout candidate carries a great deal of risk, particularly those pitchers who haven’t cleared the injury Nexus. For instance, Jake Peavy’s breakout rate as a 22-year-old was 8 percent, according to PECOTA. But when Nate forced the system to age him three years, giving him all the same stats and history but declaring him 25 years old, the system tripled that breakout rate, while substantially cutting his collapse rate.
Key Quote: “The Breakout scores are driven by a half-century of empirical data, and over the long run, ought to be roughly accurate; one out of five players with a Breakout score of 20% will go on to have a breakout season, and so on. PECOTA has no way to distinguish the one player from the other four; a good scout might. Scouting and statistical analysis are sometimes presented as opposing approaches to player evaluation, but there is no reason why that need be the case. Baseball has reluctantly entered the information era, and the ability of teams to use both types of analysis in concert with one another will be a key driver of success.”
Joke (?) I didn’t get but that probably tells you a bit about Nate Silver: "I tested the injury nexus theory by prematurely aging Peavy by exactly three years and re-running his PECOTA projection; all of his other statistics and attributes were left intact (as a college sophomore, I tried a similar trick with a scanner and an early build of Photoshop, but without so much success)."
On the Nate Silver Must-Read Scale: 1