To say the defense will be a sieve is a bit much IMO. Daniels and Binns return. Yes, Klug, Ballard and Clayborn are gone. Huge losses.
Just like losing Kroul and King were huge losses, and we wondered what we were gonna do there. Just like after Iwebema and Mattison moved on, Ballard and Clayborn did a pretty good job.
Part of Iowa's system, and how they play defense, is beneficial for younger players being able to step in and produce at a higher level more quickly...because it's a straight ahead philosophy..its team defense. It's gap control, it's doing your assignment.
The stuff that people complain about at times is the very reason that Iowa has also won more games than all but 13 BCS conference schools since 2001.
Since 2001, Iowa's worst national scoring defensive rank was in the 40's and they have averaged 17th.
The offense is going to have to score consistently next year, but I don't think the defense is going to be a sieve at all. Return Binns, Daniels, Hyde, Prater, Sash, Morris, Dibona, Nielsen among people that have started games this year. That's six returning players with significant starting experience in your back seven, and two of your front four. That's 8 out of 11 that have been there and started for this defense. Lebron Daniels has been in this year for some decent reps. they are high on Bigach and Alvis, too.
There is a lot of talent in this program. While I would not project next year's D to be as good as this year's D, which is not as good as last year's D, they will certainly be good enough to finish in the upper half.
And I think Iowa will have more playmakers available in the backfield next year...as long as they stay healthy, dangit!