The increase in sacks last season actually came from scheme changes with Tomlin/Butler vs. Tomlin/Lebeau. Particularly from the use of DB's as blitzers.
During the Cowher years (1992-2006) sacks came from the following:
D-Line: Average 11.6 sacks/year (High 16 in 2002, low 5 in 2000)
OLB: Average 19.1 sacks/year (High 26 in 1994, low 12 in 2003)
ILB: Average 6.1 sacks/year (High 11.5 in 1994, low 1 in 2000)
DB: Average 6.9 sacks/year (High 10 in 1999, low 1.5 in 1995)
Tomlin Era:
D-Line: Average 10.5 (high 15.0 in 2015, low 6.5 in 2011)
OLB: Average 20.2 (high 33.5 in 2008, low 14 in 2013)
ILB: Average 7.2 (high 10 - 3 times, low 3 - two times)
DB: Average 2.9 (high 7 - 2 times, low 0 in 2014)
If you notice, it's not much different in you add up D-Line and OLB: exactly 30.7 sacks/season for both coaches.
What has changed is how the team has blitzed. As many of us here have noticed, our team really became reliant on the X-Cross ILB blitz from around 2009-2012 as the OLB pressure started to become less effective (Woodley's decline and injury situation). Sometimes it was blatantly obvious when that blitz was coming and it wasn't nearly as effective per attempt.
Last season, the team really bumped up using their DB's as blitzers again. For most of Tomlin's tenure his impact on secondary coverages has been very conservative and (except for Polamalu at his peak in 2010) made them completely off-limits to Lebeau as blitzers. You see that in the drastic reduction of sacks/season by the DB's on this team from the Cowher era vs. Tomlin era.
That changed last season when we went back up to 7.0 sacks from our DB's.
There is no doubt we need more edge pressure as well. Our average 15.9 sacks/season from OLB's over the last 4 years is a low point since 1994. But the D-line is doing it's part consistently now and we just need to continue what we did last year by keeping the blitzing a bit more unpredictable and have all parts of the defense (D-line, OLB, ILB and DB's) contribute to getting pressure on the QB and getting some hits on him.