"Good Giants defense" = 32 in YPG, 31 against the run, 28 in PPG, 27th in takeaways, and 29th (
before yesterday) in DVOA.
The defense didn't quit against SFO because of the offense (the offense was actually tolerable that game; ~380 yards, 21 pts, 32 minutes TOP); some of the secondary quit because they were mutinying against McAdoo.
They gave up 370+ yards passing to Trevor Siemian when they played the Broncos; the only reason Denver didn't score more was because of a few breaks and their own fukk-ups.
Literally the only good/"good" offense they've shut down since the beginning of the year was the Chiefs and they needed the worst wind day Metlife has had since it opened and whoever was calling plays for KC being braindead to do it.
Regarding their talent level: Jenkins has been playing on a bad ankle for most of the season and has been out for weeks now with surgery on it. Collins hurt his ankle last week and tried to play, but had it give out on him early, making him a total nonfactor yesterday. DRC is my dude, I saluted him for helping with the fire McAdoo cause, but his jumping routes directly led to a wide open TD yesterday. They have no LBs. Their non-Collins safeties are trash. Their pass rush is absolutely pathetic.
Still, if you're going to blame anyone (and almost no Giants fan wants to win games right now anyway, so why) for yesterday, you only partially blame them and you definitely don't blame the QB that went for 430 yards with 3 TDs while getting the ball out in ~2 seconds because he threw one pick that was just as much the WR's fault as his; you'd blame the Giants' WOAT special teams, which haven't gotten anywhere near as much shyt as they deserve this year thanks to the fukkery on offense and defense.