I never implied your assumption was based on attendance, so I don't know where you got that from. Rivalries have alot to do with game atmosphere and are not necessarily based on results, although close results always intensify things (To correct you though, "last year, 5-1" never happened. It was 3-1 first game and then 3-2 in double overtime).
I can also provide some proof that despite results, the PG-PW rivalry is just as intense as ever. PG-PW basketball games this season are perfect proof (PG went 0-5 against PW), and no matter what previous soccer results are, the PW game is always PG's most looked forward to game. In fact, this year's game was Senior Night for PG. This rivalry feeds off of other sports and gains its own intensity not only from results but from tensions, atmospheres, and emotions that are firmly rooted no matter what the results are.
I know nothing about the BL-CN rivalry and as such, I will not make statements comparing that rivalry to any other. I was merely trying to point out that perhaps witnessing a PG-PW game might make your opinion more credible because you made a risky assumption (based, as you said, entirely on results, which are not always reliable indicators) in saying that "pg-pw isn't on the same level as cn-bl."
