The 49ers are in need of an interior upgrade... on both sides of the ball.
You can probably spread around the fault for the San Francisco 49ers' capitulation to the Houston Texans on Sunday amongst several units.
Receivers dropped passes, corners failed to cover, which was especially egregious considering the Texans had (at best) two NFL-calibre receivers playing in the game, and no one on the Niners offense besides Mac Jones really sparkled.