92 of Lamb's yards came from a play where Barnes missed the tackle on Dak and the CB fell down. While the Rams have good receivers, they aren't Jefferson or even Lamb. I feel the Lions match up better against Kupp because they have good safeties and nicklebacks. The one Jefferson catch in the end zone in the first game had the lowest probability of being caught in his career. Part of the reason Mullens racked up a lot of yards is because the Lions shut down the road, got an early lead, and forced Minnesota to throw jump balls. Mullens has also racked up yards before in his career. In 8 games in 2018 for SF he averaged over 280 yards per game including a 400 yard game against Seattle. We are also forgetting that the Rams secondary may actually be worse. Their pass defense is not good and their safeties are definitely worse.
Playoff experience means nothing. Goff has plenty of playoff experience. That's the one position where it might matter. Stafford had 3 playoff games in 12 years before winning the Super Bowl. He faced Burrow who had no prior playoff experience.