To me, we have four safeties who we've seen work extensively: Meriweather, Chung, Sanders, McGowan. I rate their general performance (not just 2010, obviously) in three major areas:
Deep coverage (centerfield, over the top help for CBs)
Intermediate coverage (over the middle)
Run support ( reading properly, shedding blocks, wrapping up well)
On a 1-10 scale, then:
Meriweather: 8.5 deep, 5.0 middle, 3.0 run
Sanders: 7.0 deep, 7.0 middle, 7.0 run
Chung: 5.5 deep, 7.0 middle, 8.5 run
McGowan: 2.5 deep, 4.0 middle, 8.5 run
The rest of the safeties - Brown, Page, Barrett, Lockett - I really haven't seen enough of them to rate them.
My feeling is that safety performance results were negatively skewed by a couple of things in 2010.
First, Arrington needed a lot more help along the sidelines than Bodden would have. Butler would have needed no less help and Arrington was playing in his stead because he's better in run support. Just as Chung/Sanders were playing extensively as the 5th DB over Butler/Wilhite, NOT because their coverage skills are superior, but because their run support is.
Beginning to catch a theme here?
There appeared to me to be a much greater than usual focus on run support among the safeties that, I believe, hampered our coverage. We faced a lot of strong running teams and RBs this season, AND, our D-line was a sieve.
Wilfork had 38% of all 152 D-line tackles. The next best guy was G.Warren with 17% (he couldn't handle DE at all, which is why he and Wilfork swapped). Next was Brace with 15%. The other five JAGs split the remaining 30%. That 152 TT by the D-line represents about a 35% dropoff from our 10-year average, lower than our previous low by nearly 20%. Through 2009, just the three guys in our 30-front averaged about 10% more tackles than that - just three guys averaged more tackles than all eight got in 2010.
So, for me, the main explanation for poor coverage by safeties and LBs over the middle, the reason why Mayo had an extraordinary number of tackles (a fair number of which were preventing even more YAC), why Ninkovich was biting on play-action so often, and why the pass rush was so tentative and ineffective (hesitation kills your first step whether you have a great one or not) was that focus on stopping the run to compensate for a truly dreadful D-line (which, other than Mike Wright, also couldn't generate much QB pressure).
Fix the D-line. Get Ty Warren back healthy at LDE (at least he can tackle). Upgrade the RDE spot with a high pick. Put Wilfork back in the middle where he does his best work. It'll probably surprise a lot of folks how many other parts of the defense then fall into place and "improve".