With regard to the Isles dynasty teams, two players who come to mind immediately are Wayne Merrick and Gordie Lane.
Both pedestrian NHLers, really. Merrick, a respectable, yet ordinary third-line center, Lane a third-pair dman. But both elevated their games come the post-season, particularly Lane. Stats wouldn't suggest so, but those who were there remember.
Another oddity was the ability of Ken Morrow to find the net in the most pivotal moments of the post-season. While a superb defensive defenseman, he barely possessed a slapshot and at that it barely could break a pane of glass. (He averaged scoring as couple of goals a season, typically.)
Yet his shots found their way through on multiple occassions in critical playoff games. Two that come to mind were Game #3 in the first round of the 1980 playoff series v. LA in OT. Isles were trailing late in that game, and if they lost would have been one game away from elimination, on the road. And remember, this was before they won any silver, so the monkey was firmly on their back. A Morrow floater from the point won it. And, of course, there was the famous goal vs. NYR to win that playoff series in '84.