EHM The Blue Line

I'm currently playing the NHL in '1998-'1999 retro rosters and it's great.

But I'm having a problem similar to playing with all other rosters. How the heck am I going to start losing games? Winning the President's Trophy every year with a clear margin and taking the cup in most years always kills the fun at some point.

Of course I could only recruit bad players on purpose, make tactics that suck on purpose and so on. But how do I make things actually realistic?
I'm playing the Pens now and of course Lemieux and Jagr are absolute machines. But if the rest of the team is average or below, the result should not be winning 95% of all games. How do I combine the presence of two star players and have them have a realistic effect, but still not win every game?

I am trying to not play the AI with trades; only make realistic contracts, not cheese in any other way either. I'm just wondering if there's any way to lose more games without opposite cheesing i.e. playing without a goalie or something.

try to start game with nashville or minnesota (expansion teams)...

That would work but I'm trying to look for more realism.

I traded away every good player I had apart from Lemieux and Jagr and I sill win 95% of my games. My team is not strong so it must be that the other teams are super bad. Or something. Honestly I don't know how to fix this issue.

I started to reducing my influence on the team's tactic. I just change few vary basic things in the personal tactics screen just to see how my star players fulfill their potential, but no matter what I don't lower the level of aggressiveness or hitting and I avoid the "barrage shooting" option as this seems to be unrealistically effective.

Don't use tactics at all. Relying heavily on the coach you choose and allowing them to set the lineup

well you could always try for a perfect undefeated season in both regular season and playoffs for a challenge.