Sometimes the "narrative" behind these awards changes with time. My impression is that in the late-70s-to-late-80s, there was kind of a thing where voters wanted to give certain awards (like the Conn Smythe) to "non-obvious" players. This was also before advanced-stats and the Internet, BUT there were a lot of teams and not all voters could watch all the teams' games, and consequently the "media narratives" were more powerful than now. If a media narrative got built up at just the right time, it could swing a vote towards a certain player.
For example: So powerful were the Habs by 1978 that Montreal newspapers not only predicted they'd win again in 1979, but also stated that Bob Gainey should win the Conn Smythe (they said this before the playoffs in 1979 even started). After Montreal won the Cup, who got the Conn Smythe? Bob Gainey.
With idiots like Stan Fischler on their anti-Gretzky crusade c.1983, the best those creaking fossils could hope for was that a rugged old-school Howe-like player, such as Messier, could win the Conn Smythe in 1984. (Not saying Messier didn't deserve it, but the media narrative helped that out.)
And I think Big Phil brings up a good point about the Finals. To me, the Conn Smythe should be a player who performed really, really well -- maybe the best on either team -- in the Finals. Not to dismiss the earlier three rounds, which are certainly under consideration, but the Finals is where it counts. The Finals is also, in some cases (more so in the 70s/80s), the only round some media-watchers saw a certain team play. I mean, did Vancouver media writers really watch all the Islanders-Rangers first-round games in the late 70s/early-80s, which started at 4:30 pm in Vancouver when they were still at the office, and mostly weren't broadcast on local TV? Did Stan Fischler really watch all the Kings / Canucks / Oilers / Flames games in the early-80s, which started at 10:00pm in New York when Fischler was taking his Metamucil and going to bed?
The culture of these awards has changed since, maybe, the Gretzky trade forward, as the League has become very corporate. Everybody can watch or re-watch all the games now, the complex stats are instantly available, and the League in general seems desperate to give awards to the biggest name players rather than giving unique selections to players that raised their play in the Finals, like Goring did in 1981.