Warren Sharp of Sharp Football put out his Almanac, which takes a deep dive into previewing each team. The stats and information Sharp provides are second-to-none. You can pick up a copy here if you are interested.
In his preview of the San Francisco 49ers, he is very complimentary of the four-win team from a season ago:
The 2018 49ers were one of the best 4-12 teams in recent memory, but I would excuse you for having no memory of them at all. Both of their Sunday night games were flexed out, and their other two primetime appearances came without franchise quarterback Jimmy Garoppolo, who was lost for the season to a torn ACL in Week 3.