I don't know if those can be blamed on a coach.
His job is to identify and coach up the players so that they execute. A mistake here or there is on the player but if your units are sloppy, out of sync and making consistent mistakes in different ways, thats a coaching issue.
Shit if Jeff Fishers teams didn't make so many mistakes they might have had a plus .500 season or two but because he wasn't a good enough coach, they didn't.
Bonamegos job isn't easy. And its possible he gets better. But as of so his STs have been a disappointment and the only even decent performer is Hekker who was great to begin with but he certainly isn't any better under Bonamego either.
McVay will move fast in the off-season to replace him IMO unless Bonamegos units really play great from hear on out.
I mean, Matt Gay was hired on Hekkers recommendation. When the HC decides to let his punter pick the next kicker instead of the STs coach who had blown it twice already, that says a lot.