The entire San Francisco offense is on my fallers list following Week 3. I like doing this. Don't hate on blanket statements, they can be efficient sometimes. It shouldn't be news to anyone that the 49ers were absolutely embarrassed in Week 3 against the Arizona Cardinals.
The 49ers are an interesting case. One couldn't get much lower than their offseason, losing so many key pieces, and then their Week 1 opener was dominant. Carlos Hyde steamrolled the Vikings and the defense shut down Adrian Peterson and company. Weeks 2 and 3 are trending way down, with Week 3 being one of the more disgusting showings of the year.
Kaepernick looked awful and made poor decisions to put SF in an early hole. Hyde hasn't gotten anything going, averaging 3.4 yards per carry these past two weeks. Anquan Boldin, Torrey Smith (sans the one 75 yard bomb), and Vernon Davis are all struggling as a result as well. Pittsburgh's defense should have been gashed in Week 2.
Arizona's defense is legitimate, though a professional team has no excuse for engaging "dumpster fire" mode like that. In the next three weeks they get Green Bay (at home, luckily), the New York Giants, and Baltimore. We'll see what they've got, but they are trending downwards right now.