I count 16, too:
RDE/DE - Jones, Carter/*Francis, *Bequette
DT/NT - Wilfork, Love, Brace
DT/DE - Fanene, Deaderick
LDE/OLB - Ninkovich, Cunningham
WLB/ILB - Mayo, *Fletcher
MLB/ILB - Spikes, *Tarpinian/*White
SLB/OLB - Hightower, *Carpenter
* ST role
Our starting 7 looks elite for the first time in years, with Jones, Wilfork, Fanene, Ninkovich, Hightower, Spikes and Mayo. Fast and explosive. No obvious weak links. No more Guyton! No more Banta-Cain! Thank hoodie.
Case:
Ninkovich lines up in a down position, but drops into coverage post snap. Mayo picks up the RB releasing through the middle and Spikes rolls into the flat to fill for Hightower who is rushing from his LB spot. Love and Jones play a twist on the right side to get the LT flustered enough that he doesn't notice Hightower coming off the edge. The QB panics, reading the extra rusher from the left, lobs it to the TE on that side where he figures the defense has cleared out. Spikes steps under it for a clear sailing pick-six.
The positional versatility across all seven players means that, even tho everyone is stunting or filling a different role than their normal assignment, they're all still doing something they're good at, have done in the past, and have trained for. What defensive coordinator wouldn't be drooling at the different looks you can create with the same base personnel? You can create all kinds of match-up problems. You can run 4-3 or 3-4 without substituting a single player.