A weekly look at what the 49ers must fix:

You knew the San Francisco 49ers' pass rush would suffer early in the season with outside linebacker Aldon Smith serving a nine-game suspension. But the lack of a relative threat thus far has been shocking, and the Philadelphia Eagles, who boast a quick-hitting, high-scoring offense, could present a recipe for disaster for the Niners if they can't figure it out -- and quick.

"Obviously, when you win, nobody pays attention to those plays that you could play better at," said inside linebacker Patrick Willis, who is without a sack this season and was called for a critical and questionable roughing the passer penalty on Sunday.

The 49ers have only four sacks this season; Eagles QB Nick Foles, who leads the NFL with 978 yards passing, has not been sacked since Week 1. In fact, so invisible was the 49ers' pass rush against the Arizona Cardinals on Sunday, quarterback Drew Stanton had so much time to throw, his average depth of target was 16.7 yards, the highest such figure of any quarterback since Tim Tebow's 16.7 in Week 11 of the 2011 season, per Pro Football Focus. Plus, 13 of Stanton's 33 pass attempts were at least 20 yards downfield, the most by any quarterback this season.

Not even blitzes were working against the Cardinals, as the Niners brought it on 14 of 40 pass plays, including plays wiped out by penalty; they Niners also rushed six players three times and twice they brought seven, per PFF.

The Niners, who did not blitz a defensive back at all in Weeks 1 and 2, sent Jimmie Ward seven times and Perrish Cox four times.

Blitzing that much against the Eagles might be playing into their hands.