I dont think they were more disciplined, they just didnt get called for the stuff they were doing. It wasnt as bad as the Boston series, but it will be a factor to keep an eye on as the series progresses. Panthers need to stay out of the box, or at least have the calls evened out, in order to win the series.
Im not saying that the whole team is soft, but from watching them, the last few seasons I believe that throwing the body takes them off their game a bit, or at least some of your top end players. And when its the playoffs, and things are not as wide open as the regular season, that can take a toll on those players. Nylander for example, who is great offensively, is a bitch IMO, and I think the Leafs could fare better in games overall if he was a bit more willing to play the body.