The 49ers have been prepared for a deep playoff push

Remember the stat that pointed out that the team with the longest unbeaten streak does not usually win the Super Bowl? I would like to suggest that one of the reasons, is that the team that only plays weaker teams due to strength of schedule or rarely has a close game is not emotionally prepared for the challenges that they will face in the playoffs. Also, consider that the 49er team is young, and for most of their players has next to no playoff experience. They don't know what the playoffs are like - but in fact, they actually do, due to the schedule that they faced. They have already faced 3 of the other 5 teams that will most likely make the playoffs (4 if the Rams make it).

Against Seahawks - This was a playoff atmosphere game. The Seahawks came ready to play. Even though they had a poorly ranked defense, they were near unstoppable. The emotion in that game was extreme. Game went to overtime, and Seahawks win with a FG as OT time expired. The 49ers played a close match until the end.
Green Bay - Very strong offensive team, that was humbled by the 49ers in a blowout. Defense carried the day.
Baltimore - Likely team to be the AFC representative in the Super Bowl. 49ers played them to the final seconds, once again losing to a FG.
Saints - Defense failed them, but they matched Brees score for score, winning a shoot out with a field goal of their own as time expired.

The 49ers can win games with their defense. They can win games with their offense. The running game can blow out opponents with JG as game manager, or he can take the team on his back and throw 4 TD. The Packers, Ravens, Saints three game stretch is the most brutal late game stretch that a team has ever faced, 2 on the road, and the 49ers went 2-1. It should be noted that they basically went through a playoff run during that 3 game stretch. The next 3 game stretch that they will face like that will be the playoffs, and it won't be anything new.

It should be noted that playing Baltimore may pay huge Super Bowl dividends. Remember when Patriots were going through their unbeaten season? Late in the season they faced the NY Giants and beat them. However, they faced them again in the SB and lost. The Giants learned from their loss and were ready to take on the Patriots in the next game. It is also why the Cardinals play us so tough even though they lose most of their games. The more you play the same team, the more you understand them and their weaknesses. However, Baltimore has a big weakness in that their offense depends so greatly on Lamar Jackson. Everyone was saying before that game that you can't practice on defending Lamar Jackson, he is too fast. However, now that the 49ers have played against him, they won't be so surprised by his speed when they face him again.

This isn't a young team any more. They are now battle tested, and ready for anything they see in the playoffs.