Kris Letang, PDO, and the difference between being unlucky and bad

Among the many problems the Pittsburgh Penguins have so far in the 2017-18 season, PDO is probably #1.

For those not fluent in the fancy stats, PDO has a dictionary definition of:

PDO, called SPSV% by the NHL, is the sum of a team's shooting percentage and its save percentage. PDO is usually measured at even strength, and based on the theory that most teams will ultimately regress toward a sum of 100, is often viewed as a proxy for how lucky a team is.

Basically, it measures luck. Over a long period of time, you would expect a normal team to have their shooting and saves balance out at even strength.

This season, however, the Penguins have been abysmal and last in the league in PDO as they’ve…