I watched Harris in the Senior Bowl, and quite honestly I like Harris as a SILB. Harris just worked his way through trash and was impressive. Harris just seems to have that "it" factor. I remember noting that.
This is an important determinant for success as a 3-4 ILB:
How well can you work your way through trash?
In order to do it well, the ILB needs:
Field intellegence, partly born from experience
Hand-eye coordination
Nimble feet
Short-area quickness/explosiveness
Size/strength
Sideline-to-sideline speed
This may be why it can be tricky to project a college DE, OLB, even MLB to 3-4 ILB: some of the skills required to play the position well are inherently unique to that position. Evaluation is therefore comprised less of anecdotal evidence, and more of instinctual reliance.
For instance: many of us feel fairly comfortable with projecting Stewart Bradley to ILB. But has he ever had to deal with the action taking place smack dab in the middle of the field, to borrow from Tennyson, with 300-pounders to the right of him, 300-pounders to the left of him, 300-pounders in front of him? At the same time?
Based on what I know, what I think I know, and what I don't know, I have narrowed my choices for 24 and 28 to the following:
CB - Chris Houston, Aaron Ross
LB - Paul Posluszny (David Harris is tempting, but...)
FS - Michael Griffin, Reggie Nelson (Brandon Meriweather has a lot of splainin to do first)
Unless Joe Staley is the LT of the Future, then 24 and 28 are defense and defense.
LaRon Landry and Leon Hall are top-12, and cannot be had.
Darrelle Revis and Patrick Willis are top-20, and can be had only via trade-up.
If all of the aforementioned are already of the board, then I would entertain offers to trade down, or out to 2008.
The rest of the usual suspects are either too inexperienced, too inconsistent, or too incorrigible to warrent (bottom-fourth) first-round consideration, David Harris notwithstanding.