Indeed, everything I've seen suggests that Steve has done a great job with the secondary, he's been key to developing players like JC Jackson to bolster our depth in that area. And he's done well to integrate veterans like Gimlore, Jason McCourty, etc seamlessly into the unit.
Yes he is coaching a positional unit that his father has invested heavily in. And Steve has 3 Superbowl rings to show for it. To me, that makes it clear that son or not, Steve's unit does its job.
Frankly, people like Gilmore, Harmon and the McCourty brothers played an absolutely huge role in our latest Superbowl, and credit for that goes right to Steve. Without the secondary going balls out we don't beat the Rams. Especially Jason McCourty's strip and Harmon's blitz to force the pick to Gilmore. Steve's unit gave the team as much as a 14 point swing on those plays alone, absolutely a difference maker.