Problem was SF couldn't block Jones. He was the difference maker, took 2 likely SF TD's off the board with pressure. Brock played well enough to win, but they just had a few too many things go against them last night.
There were quite a few times they were able to block Jones effectively with ONE guy. Now, some of the doubles had something to do with that, but I think it continued a string of pedestrian performances for Jones.
SFs bigger issue was how they handled blitzes/cover zero packages. They seemed ill-prepared/equipped in the 3rd when that's about all the Chiefs threw at them. SF didn't call the right plays for it, certainly didn't block well for it, and Purdy (himself) didn't have an answer to that pressure.
If the Chiefs stayed in their based and rushed 4 guys (primarily) the entire game SF wins. I'm sure there are advanced stats for the looks/coverage, but I'm willing to bet SF's numbers against high pressure/cover 0 was terrible.
If they want to get over the hump they need to (across the board really) figure that out.