The "playoff goalie" issue:
First of all, if there's something to be done about it, the only simple and elegant solution that need be considered, IMO, is the one big_drive offers above. Only each team's top two goalies per regular season games played eligible for playoff use. We all know that sometimes you go through a season with a rotation, sometimes you use one main guy and the backup doesn't even get into 10 games. It seems to me that we don't want to be picking over our opponent's rosters, we don't want to get into a situation of saying "you can dress this guy but not start him", etc.
Now, I'm not going to be too contrarian here, but IMO I haven't seen this as a big issue. Let me just talk this out. I know it seems kind of silly to have a name show up in goal that you've been seeing around the MLD forever and now only shows up at playoff time. Yes, it looks silly and unrealistic. Well, there are a lot of unrealistic things involved here, much as we try. I think what's critical is whether or not a "playoff goalie" can swing a series, and I'm not sure. As evidence, let me present the Firebirds.
As far as I know, I was the first owner to retire a goalie under the old 350 min TOI. Morton was 100/100 and didn't win in the playoffs. I retired another 100/100 goalie, Xavier, who didn't win in the playoffs. They lost because the teams in front of them weren't good enough, couldn't score in the playoffs, that's the story of all damag sim teams, all defence and not enough goals. My best goalie ever in a short term was Darville, a guy who never had the stamina to be a full time starter, but for some weird reason had multiple extended shutout streaks in his career.
The rules we put into place this season are designed to now limit the effect of repeating stacked rosters in multiple seasons, while still allowing GMs to determine and plot the lengths of their players' careers. Over time, I suspect that will minimize any effectiveness of a "playoff goalie." I believe teams win in the MLD, not goalies and not even star players.