There are two different types of edge defenders on the Patriots roster. There are those who that offer the ability to kick inside to defensive tackle on sub packages, and those that do not. New England has absolutely loaded up on the former.
At this current point, only Rob Ninkovich and Michael Buchanan- and possibly Rufus Johnson- can be considered purely outside edge defenders, without the size to move inside. These players are perfect for the 3-4 outside linebacker role and offer additional front end flexibility to drop back into coverage to confuse the quarterback. Ninkovich is a rock and Buchanan is firmly on the roster bubble after returning from injury and with the addition of so many new faces.
Chandler Jones and Jabaal Sheard should be considered locks in the starting rotation of defensive ends and both offer the ability to kick inside in sub-packages. After multiple seasons with just Chandler and Ninkovich as the defensive ends, adding a third body should keep them all fresher later in the game.
The selection of Trey Flowers adds a fourth to the rotation, which gives Jake Bequette (and Buchanan and Johnson) a much steeper uphill climb to make the roster. Flowers was one of the most productive overall edge defenders coming out in the draft, but offers some limited physical upside. He wins with his strength and his stoutness and his relentless attack should be a perfect fit in this newly designed defensive line.
If we consider the group of Chandler, Sheard, Ninkovich, and Flowers to be roster locks (as they should be), then there's very little space for additional edge defenders to make the roster. All four should be utilized in heavy rotation in base sets, with any combination of Jones, Sheard, and Flowers kicking inside on passing downs to provide extra value and quickness in attacking the quarterback.