From my own amateur perspective:

Strengths

RB - Return Zac Stacy who broke the school record for rushing yards last season.  Also get former SEC FOY Warren Norman back after redshirting last year due to an injury.  Also return Sophmore Jerron Seymour who saw carries last season behind Stacy.

QB - Jordan Rodgers returns after taking over the starting job after the Georgia game last season.  He was a key reason why Vanderbilt became much more productive on offense during the 2nd half of last season while entering the meat of the SEC part of the schedule.  Austin Carta-Samuels will be competent replacement for Rodgers should that be necessary.  He is a former WAC FOY while at Wyoming and has had a year to learn the offensive schemes after sitting out a redshirt transfer year.

WR - Vanderbilt returns all starters back from a corps that accounted for 13 TDs and nearly 1700 yards.  That was a huge improvement from barely reaching 1000 yards and a couple of TDs the season prior.  Now in the 2nd season with the new staff, an improvement over last season should be expected.  Look for Chris Boyd and Jordan Matthews, who accounted for all 13 TDs last season, to have big years.

CB- Though we lost CB Casey Hayward and S Sean Richardson to graduation and the NFL, I still see the secondary as a strength on the defense due to the quality depth that has been created at the position.  Trey Wilson returns after a breakout season opposite Hayward last year.  Andre Hal is expected to fill-in nicely for Hayward at the other CB after a couple of years backing up the position.  Steven Clark and Eddie Foster are considered quality backups with experience.

Weaknesses

OL - After losing only 2 starters on the OLine, there is still some question of depth at the position.  This was enough of a concern following last season that the Coaching Staff went out and signed 6 OLine recruits in February.  Wesley Johnson is an All SEC 3rd teamer at left tackle.  Last season he had to play nearly every position on the line at some point due to need.  Ryan Seymour and Josh Jelesky are considered solid at both guard positions.  Andrew Bridges looks like he will man the other tackle after seeing a lot of PT as a Freshman.  Spencer Pulley will be the new starting center after backing up the position as a Freshman last season.  After that there are some question marks with regards to 2nd and 3rd teams.  Still the coaching staff considers this OLine to be way ahead of last season's.

DE - It will be hard to replace 7th round NFL draft pick Tim Fugger.  Walker May seems ready to step into that roll.  Johnell Thomas returns for his Senior season along with Junior Thad McHaney bringing experience to the position.  After that there is a lot of youth. 

LB - Linebacker was considered thin last season and now it is without last season's defensive captain, Chris Marve.  Archibald Barnes and Chase Garnham return as starters and should be expected to anchor the LBs.  Also return is Tristan Strong from a season-ending injury along with productive Karl Butler.  There will be some concern with depth as the remainder of the group will be Freshmen.