Every year, the NHL hands out awards to its most outstanding players of that season, giving the top three vote-getters for most of them the status of "finalist." The award for the best defenseman is called the Norris Trophy.
The defenseman has been key to his team's success over the last decade. Eight of the Western Conference champions have had an elite blue line, as have most of the Eastern Conference champions.
So what if we awarded a trophy for the best defenseman of the entire decade? This would certainly favor those players who were on the ice for most of the past 10 seasons (2000-01 through 2010-11, minus the 2004-05 lockout) and count only those seasons. Since picking three finalists would be too obvious, the list is expanded to 10 to make it more interesting.