I'm a Saints fan who registered to this forum in hopes of our two teams meeting in the SB that year. I have lurked over the years since I have friends in the NE area and people I know who were friends and part of my family.
This is a topic I've had years to think about.
The 2018 team had a fatal flaw where the offense quit clicking in the final month of the year. They were never the same again after the TNF game at Dallas. Brees' arm strength collapsed towards the end of the year, and they went from averaging 27 points a game, down to just 14-16 in the final month. Pull up the schedule and look at the last games of the year. The Steelers game was the last time the Saints offense looked OK, and that game had some controversial calls in it that went our way that didn't go without discussion at the time.
What happened in that game vs Dallas was that they took away Kamara and MT, leaving Brees to throw to a bunch of no name guys that people don't remember. Go back to the non-call and look at who he was throwing to. Who is Tommy Lee Lewis? Once you removed Kamara and Thomas, the offense lacked another playmaker to scare opposing defenses with. In December, the Saints tried to sign Dez Bryant in desperation to have another playmaker, and he got injured in practice.
The week before the fated non-call, they struggled to put the Eagles away. The same team they dropped 40+ points on at the end of November.
It was like the offense just broke after the Dallas game and they never quite got back on their feet.
Do I think the Saints would've been a tougher opponent? Probably not. They played a lot of zone defense back then, which the Pats were great at carving up. Gronk would've had a big game against us. On the other side, taking away Kamara and Thomas would've boxed up the offense like teams were doing at the end of the year.
I wasn't confident about facing the Pats had we reached the SB. Even in the non-call game, the Saints led 10-0 and then 20-10 and still couldn't put that Rams team away. Even after the non-call, they let them drive down the field and kick a FG to force OT. We also won the coin toss in OT and threw a pick.
My gut has always told me the Pats would've won comfortably, even with a closer score. The offensive struggles the Saints had didn't bold well for this game. I think the Saints would've struggled to score 20 points and probably lost 24-13.
Good luck in this coming SB. Rooting for you!