Regular-season performance and playoff success
Alan Reifman, author of the "Hot Hand" blog, comments on NHL and NBA performance in a recent New York Times article.
He tells us that when you're trying to predict playoff success, regular season performance is a much better indicator in the NBA or the NHL. Reifman ran correlations between regular season points and playoff rounds won. Here's the NHL:
2007 NHL Playoffs: r = .50
2006 NHL Playoffs: r = .04 (.22 excluding Detroit)
2004 NHL Playoffs: r = .31
2003 NHL Playoffs: r = .33
2002 NHL Playoffs: r = .50
And the NBA:
2007 NBA Playoffs: r = .33 (.58 excluding Dallas)
2006 NBA Playoffs: r = .67
2005 NBA Playoffs: r = .71
All this is as expected: NBA games are more predictable in the sense that the better team wins more of them. If NBA games were shorter, or had fewer possessions, the numbers would be closer.
Also affecting these correlations is the relative strengths of teams in playoff matchups, but my impression is that these are roughly equal between the two leagues.