1) There are other Corners later in the draft that fit the Jaguars scheme better, due to the depth of the class.
Jaguars Head Coach Gus Bradley's scheme demands several things from his Corners; Ability to constantly play press coverage, Above Average Height, and Arm Length. Milliner has the Height (6'0") and the Length (32" arms) that Bradley coverts in his Corners but on tape, there are several other Corners in this draft that fit the scheme better due to their ability to play Press Coverage. Milliner is a good corner in most coverage's, but when put in press coverage he had his struggles. Quicker receivers beat him off the snap and he could not keep them in check, while other corners such as Blidi Wreh-Wilson, Darius Slay, Johnathan Banks, and D.J. Swearinger are much more adept in press coverage and would be better options for the Jaguars. Milliner is the "Consensus #1 CB" But from a Jaguars viewpoint, there are several other Corners that would be much better in this scheme and are clearly better options.
2) More pressing needs, such as QB and Pass rush.
There are more pressing needs the Jaguars have than Corner, at least in this draft where the Corner position is VERY deep. The Jaguars have not had any type of pass rush for years, and there are several athletic pass rushers at the top of the draft that fit their scheme such as Dion Jordan, Barkevious Mingo, and Ezekiel Ansah. Also the Jaguars biggest hole is the most important position in football; QB. Blaine Gabbert and Chad Henne are clearly not the answers, but Geno Smith has Franchise QB potential, and who the Jaguars appear to have taken a liking to. There is no way you can make a argument that taking a CB at #2 is more important than finding a potential franchise QB.
My point is, the Jaguars have more pressing needs at the top of draft this year than CB. Milliner is not even the best corner in the draft from a Jaguars standpoint, and they can address the CB position later in draft, while they should fill one of their top 2 needs with #2 pick, because the talent and scheme fits are there for them. A QB, or a LEO end should be the #2 pick, honestly it has to be. The QB position, and the pass rush in Jacksonville have been inferior for far too long, but here is their chance to begin to fix them.
3) Bradley's history with CB's.
Neither of the Corners that Gus Bradley coached in Seattle, Richard Sherman and Brandon Browner, were considered high profile prospects. Sherman was a 5th round pick, while Browner was undrafted. But both play like 1st round talents in Seattle, because of how good of a fit they are in Gus Bradley's scheme. Sherman was passed over by all 32 teams until the lower half of the draft, But today he is one of the best Corners in the Draft. Gus Bradley corners are not typical NFL corners, and could very well fall on draft day and fall right into the Jaguars laps. Bradley's corners can be found late, so there is no reason that the Jaguars should take one at #2. There are several corners this year that could be found later in the draft that could turn out to be top notch Corners thanks to Bradley's scheme, a Corner at #2 just would not make sense.
So basically, I think the Jaguars will not, and should not, take Dee Miller at #2 because of how deep this Corner class is, Milliner is a not a very good scheme fit, The Jaguars have more pressing needs at #2 (Leo, QB) and Bradley has a history of being able to find Late rounders that fit his scheme perfect, which he should be able to do this year.