Much is being made of the fact that our pass defense ranks dead last (120th) in yardage allowed (1539 yards in 5 games, or 307.8 yds/gm). But the sky isn't actually falling. As has been pointed out elsewhere, the "yardage allowed" metric doesn't take into account our 7 interceptions. The INTs show up in the pass efficiency rankings, where we rank 79th: not awesome, but not horrible.
There are a few other things that stand out from a more detailed look at the pass defense stats.
Attempts. We lead the nation in pass attempts against, at 206. Clearly, the game plan for our opponents has been to exploit our young secondary. The Indiana game has some impact on these stats, given how long their pass-first offense was on the field.
Completion percentage. Our completion percentage against is 60.68%, which ranks 77th. Again, not awesome, but not horrible.
Interceptions. We have recorded 7 INTs, which ties us for 16th place with 11 other teams (though 5 of those teams have played 4 games). We are averaging 3.4 interceptions per 100 attempts, which ranks us 57th: above average!
Yards per attempt. We are averaging 7.47 yards per opponent attempt, which ranks 91st. That's not so hot, but hey, at least we're not #120!
Touchdowns. We've allowed 8 passing touchdowns, for which we are tied for 83rd (higher rank = less touchdowns) with 9 other teams. Passing touchdowns per attempt against is 3.88, which ranks 48th (less touchdowns = higher ranking).
I think these statistics basically reflect what we've seen on the field: a willingness to concede the short-yardage passing game in exchange for fewer big plays and more interceptions. Given our personnel, this isn't a crazy approach. And there is opportunity for upside, if players are able to improve with their game experience.