The 49ers lost a lead, as they were up 23-10 at halftime but ended up losing 24-23
It was reportedly a "historically hot day" in the South Bay
The word "Crumbling" alludes to the 49ers' tendency to fall apart under pressure, as mentioned in one of the articles: "What do the San Francisco 49ers and a cookie have in common? They both crumble when the pressure is on.
"Another" refers to the fact that this is the second time this season the 49ers have blown a double-digit lead to a division rival.