I know that the metric isn't perfect, but Lindberg was outplayed by Bob Froese for pretty much all his career (even during his ... I don't know if Froese only got the start against bad teams, and that Lindberg outplayed him during the playoffs (really small sample size)) but still...
Not mentionning that the Flyers, as a whole, tended to make their goalies look a little better than they actually were during the 80ies. Yeah, Lindberg was really good in the 85 playoffs, but pretty bad in the 83 playoffs (worst than Froese or Peeters ever were, actually). When looking at Lindberg, one must not forget that his 85 run might have the best he could ever be. He was still young in 83, but not that young, in a time when it wasn't uncommon to see 21 years old goaltender play at their top.
In the end, I think it's wrong to class Lindberg as anything else than a "might have been".