First understand my expectation of the #2 pick in the draft:

Perennial Pro-Bowl player who is a game changer.  Does Marcell Dareus fit the bill?  I don't question he will be  good NFL player who will be solid and dependable.  But and elite DT that can change a game?  Lets take a look at a few items and you can decide for yourself.

Production: He has produced 11 sacks and 20 TFL's in 33 games which give him a production number of .93 (sacks + TFL's / games).  That would put him below 5 other DT's in order: Wilkerson 1.94, Fairley 1.5, Paea 1.2, Ellis, and Liuget .94.  True Wilkerson and Ellis played against less talented players.  But Fairley basic produced his number in 1 season.  Fairley and more TFL and sacks in one season than Darcell in 33 games from the same position.  And everyone schemed for Fairley the second half of the season. 

Explosion: Which is bench+broad jump+vertical.  Darcell didn't do the broadjump but benched 24 reps and had a vertical of 27'', I will be generous and give him a pretend broad jump of 9'.  That gives him a number of 60.  Believe me that is not elite.   

Now you can't just take numbers but believe me numbers increase and decrease risk.  For example Suh had a production# of 1.53 and explosion of 76.3 - a lethal combination we saw the results.  He is rare indeed.  Believe or not this year has one player with CRAZY numbers - JJ Watt had production of 1.84 and explosion of 81!! And tape to back it up!! 

Dareus does have superior balance and instincts with a great burst.  But will this make him a Pro type player?  If you expect 3-6 sacks and 7-13 TFL a year elite then yes.  But generally that's not going to cut it unless you're crazy good against the run.  Dareus is good - not great.  Needs to get much stronger (24 reps in bench proved that) and get his 319lbs solid - not the soft weight issues he has experienced. 

Scouts will put 70-80% on tape evaluations - rightfully so.  Very solid tape indeed - but is it elite?  No Fairley is elite, Von Miller is elite, Peterson is elite, Bowers is elite.  With different risk.  I think Dareus is one of the safest players with lower ceiling but low bust factor.  Is that what the Broncos should draft?

Finally couple scenarios.  Its 3rd and long and you need a play - you choose:  Fairley, Miller, Peterson, Bowers or Dareus?  Remember in a pass happy league sacks and pressure rule.  Dareus will be solid but not sure about elite.