Yeah, that would explain it... I find the viscaria works with hurricane and tenergy. But for tenergy especially, when new it has a hard feeling, you can't really feel the grip of the rubber, but within 1 month the rubber softens a bit and starts to play more sweetly. Then after 6 months to a year, depending on how much you play, the blade starts to become clear and softer, it's a blade that requires commitment, it needs time to settle and when it does, it's a dream. It goes from feeling glassy, hard and vague to feeling velvety but crisp and accurate.
On more thing I fond is that it kind of takes the characteristics of the rubbers you put on it as well, I can't really explain it. So I guess that an old softened viscaria with dead old rubbers would be super weird.