The second of a 10-part series that looks at where Pac-10 teams are strongest and weakest as they begin spring practices.
Strong: Offensive skill positions.
Why it's a strength: The Wildcats welcome back just about all their top skill guys -- their top-two quarterbacks (Nick Foles and Matt Scott), top three rushers (Nic Grigsby, Keola Antolin and Greg Nwoko) and five of their top six receivers (Juron Criner, Delashaun Dean, Bug Wright, David Douglas and David Roberts). The only loss is 2009's leading receiver Terrell Turner. Even the early departure of TE Rob Gronkowski is eased by the fact that he didn't play in a single game last year.
Weak: Up the middle defense.
Why it's a weakness: It's a weakness because the Wildcats must replace both defensive tackles, all three linebackers and free safety Cam Nelson. Moreover, they head into spring without a lot of obvious answers at those position, seeing that the defense's top four tacklers and five of the top six are all gone. Lolomana Mikaele was listed as the backup at both DTs positions at the end of last year, but he finished with just 12 tackles. Two junior college transfers, linebackers Derek Earls and Paul Vassallo, are expected to earn starting positions. Toss in new co-coordinators -- though Tim Kish was promoted from linebackers coach -- and there are a lot of questions on this side of the ball.