Keep in mind, 21 players got more sacks than Dwight Freeney last year, and Freeney got 8...
JJ Watt, K Mack, E Ansah, C Dunlap, Chandler Jones, Whit Mercilus, M Wilkerson, G Atkins, A Donald, V Miller, K Short, Everson Griffen, Mel Ingram, J Peppers, Mike Bennett, Cam Jordan, Robert Ayers, Fletch Cox, Ryan Kerrigan, C Avril, and G McCoy.
Of those players, only JJ Watt, V miller, Ryan Kerrigan, Everson Griffen, Aaron Donald, and Gerald McCoy also had over 8 sacks in 2014.
Also keep in mind that McCoy and Donald are strictly DTs.
So over the past two seasons, only 4 edge players have had over 8 sacks in back to back seasons.
Therein lies the problem.
you may also find a correlation between the consistent edge rushers, .. and their team mates inside also commanding attention on the rush.
getting to the QB is tough but it is even tougher when the offense can throw two or three blockers at you...... build the D-line correctly and the offense is then counting on an TE or RB to block your edge rusher one on one.....and that is what you hope for.