1) Changes on defense. The 3-4 front will get the most attention, but I also wonder what kind of coverages we'll use behind it. Will the cover 2 concept be completely tossed?
2) Development of offensive line. We have to see this unit improve and develop a more consistent running game. What will the next faze look like of developing into a more zone focused team?
3) WR/TE development. Good to have Nelson, Norwood, Mastrud, and Pooschke back, but it will be interesting to see who else steps up, especially at the WR position. We probably won't know until the fall though.
4) Development of Josh Freeman. How much improvement should be expected after another offseason and a year of experience under his belt? He had plenty of ups and downs last year, should be a more consistent player as a SO.
5) Playmakers on defense, especially from the LB spot. Good to see Campbell and Watts back, but who will step up as our playmaking LBs (Walker should be one) and how will DT develop. The DT/NG will be a very important spot for us if we want to be diverse up front and especially when we are in a true 3-4 look.
I'm sure there are plenty of others, but those are the 5 that stand out to me.