49ers screwed up, got way too cocky taking 2 guys who aren't even active on gameday right now. Their depth at OLB is extremely lacking and it has shown in the lack of a pass rush against better teams. Not a single sack against the Giants is utterly embarrassing. This team lacks depth at 3-4 DE and OLB, both of those positions would be helpful in terms of having a solid rotation to keep other guys fresh, this defense is not getting the same push it was at times last year and this is 2 games this season that they've looked absolutely tired and a few steps too slow on defense. With how competitive the NFL is, I don't think any team can afford to have 1st and 2nd rounders not contribute whatsoever.
I think their performances last year made them a cocky, having seen Justin Smith physically beast and dominate people and the DL getting a ton of pass rush heat in the playoffs, unlike teams like the Giants and the Ravens, this team doesn't have the depth and ability to rotate guys in and out like a 3-4 team should.