Picking at #28 is far more unpredictable than at #4. It will really depend on how things unfold for the previous 27. At this point there is almost always a player that begins a slide down the draft. What if we get a premium player at a position that is not considered a need?
What if WRs Corey Davis or John Ross slide down to the 28th position, that would be bargain value.
Then again, let's say a QB slides and another team wants to trade up and are willing to make a great deal, the Cowboys don't consider it?
The point is, a pick is only good from the standpoint of the draft if value is achieved. Realistically, we won't know until that player begins performing. The Cowboy management could get high praise for filling needs with players at that position but if those players suck, then it is all meaningless.
There was an abundance of criticism for taking Dak when the Cowboys "could have used a player capable of contributing at a position of need". turns out they did, in a huge way.
The Cowboys take a WR in round 1 and are lampooned. Before the season, they lose a starter, say Terrance Williams. The rookie comes in and becomes Dez's perfect bookend. Meanwhile, a 5th round pick of a DE gets rookie of the year despite the fact that the Cowboys were criticized for not "addressing the need at the DE position" when the 2nd round ends.
It could and does happen as we all know.