Don't wanna get into a debate about who's "soft", so let's just say players who weren't generally physical and performed well in the playoffs.
Patrick Kane
Daniel Brière
David Krejci
Brad Richards (at least for the first half of his career)
Jason Spezza
Erik Karlsson
Pavel Bure
Pierre Turgeon
Wayne Gretzky
Mike Bossy
Guy Lafleur
To name just a few. Honestly, the notion that only physical players are succesful in the playoffs is bull****. If you can take good decisions and capitalize on opportunities while having little time and space, you're gonna have success in the playoffs, regardless of how many hits you throw.