I think a pretty big tradition is the NHL fans getting insecure because nobody wants to cover their sport on TV, so they come in here and whine
Just to be fair...the Canadian viewers needs to be included since both leagues have sports teams north of the border. Given this demographic the NHL pulls in a larger television audience than the NBA. Additionally, Gary Bettman almost single handedly destroyed the NHL due to his ineptness...the league is just starting to recover from his moneyshines. Oh, here's a good article on fan enthusiasm...
NHL vs. NBA: Hockey winning in attendance, fan enthusiasm? - Puck Daddy - NHL Blog - Yahoo! Sports
Article on NBA viewing in Canada
"Then again, the NBA playoffs are barely on the radar up in Canada. (TSN's two playoff games have averaged a paltry 67,500. Rogers Sportsnet has carried three games averaging 55,000 viewers. The Score's average for its first five broadcasts is 21,000."
Now let's look at the NHL Playoff ratings in Canada...
"According to the NHL, CBC is averaging 1,268,000 viewers for 10 broadcasts through April 18, a 33 per cent increase over last season's average of 951,000 viewers. Meanwhile, TSN is averaging 992,000 viewers for nine telecasts over the same period, a 112 per cent increase over last year (467,000 viewers). "
Again, both leagues have Canadian teams so you must include ratings north of the border in order to make a fair comparison.
Oh, and you need to include the local television markets (e.g., Fox Sports) ratings since Versus (while getting better) is still a joke compared to a channel like TNT. For examples, the Chicago and Detroit are markets are each reaching 400,000 homes..and even non-traditional hockey towns like Washington DC games are reaching 300,000 homes this playoff season.
http://penguins.nhl.com/club/news.htm?id=525443