Selection bias with Derek Jeter’s fielding: bad stats, memorable moments

As Derek Jeter’s career winds down, one baseball pundit wrestles with how Jeter’s defense numbers are so bad even as we remember some of his great fielding moments:

Data-mindful observers couldn’t figure out why the decorated Yankee kept winning those Gold Gloves and garnering raves for his defense. Stats such as Ultimate Zone Rating and Defensive Runs Saved didn’t merely suggest that Jeter was overrated; they pegged him as downright terrible. Even the best glovemen lose range as they age, which means Jeter actually hurt himself by playing past his 40th birthday and seeing his career defensive totals dip as a result, but the figures are unnerving regardless. Based on Baseball-Reference’s Runs From Fielding, which is based on DRS, Jeter’s combination of subpar defense and exceptional longevity don’t merely make him a defensive liability; they make him the worst defensive player relative to others at his position in baseball history.

That ranking is incredibly hard to fathom because of a very human weakness: selection bias. People remember a few extraordinary events, then ignore or even repress the information that might contradict that initial impression. With Jeter in particular, it’s nearly impossible to make the visceral reactions agree with the data, because Jeter has pulled off some of the most incredible defensive plays we’ve ever seen.

How to put this all together?

So really, it’s OK to agree in part with both sides of the argument. Even if we acknowledge the flaws of advanced defensive stats that aren’t yet based on play-by-play data or dispute the claim that Jeter was the worst ever, we can comfortably say he was overrated defensively by many people for many years, and cost the Yankees their share of outs. But we can also say that every huge-leverage play like The Flip negated a handful of squibbers through the infield during random April games in Cleveland, even if they left him as a net-negative defender on the leaderboards. Jeter might not have deserved five Gold Gloves, but he does deserve credit for crafting memorable plays that can’t simply be chalked up to coincidence or luck.

In other words, memorable plays that lead to key victories can go a long way to wiping out more objective data over a longer period of time. Of course, this is true across a broad range of contexts beyond baseball; showing unusual urban crimes and police responses as “normal” could have a similar effect on television viewers. In the long run, perceptions may have less of a shelf life as people who witnessed those events – like “The Flip” – stop remembering them or die and the data lives on.

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