The defense was significantly dumbed down this year, but Nyles Morgan didn't set the world on fire. He had a very good year: But he wasn't a finalist for his position award, he's probably not going to be on any All American teams, and he wasn't even the defensive player of the year on his own team(and it's not like he was overshadowed by a Jaylon Smith type teammate). This comes in a season when the coaches all talked about him being the most improved player, without a doubt, from last year. So if he only had a solid year in a dumbed down defense, after improving so much; what makes anyone think that he should have been playing last year? I'm not defending BVG as a coach; he obviously has some serious flaws. But what I am saying is that people have just kind of taken it as a fact, that Morgan would have been an upgrade over Schmidt last year, when that's absolutely not a certainty.
In reality we'll never have complete certainty on the topic, as its impossible to every truly know.
However........
Over 13 games, in 2015, Schmidt had 78 total tackles (42 solo), 4 TFL's, 1 sack
Over 12 games, Nyles Morgan had 88 total tackles (49 solo) 6 TFL's, and 4 sacks.
So with one less game played, he had more production in all three areas. So, though I can't say with complete certainty that Nyles would've been better, I feel very comfortable with that belief.
I'd also add, Morgan was also used in a much less attacking manner than Joe was. Prior to BVG departing, Driskell did a breakdown of how much Joe was used to blitz versus Morgan, and it was far more. Meaning, when the more athletic player, in Morgan, was on the field, he wasn't used to attack the LOS or backfield as frequently as Schmidt was. That's the real head scratcher if you ask me. However, he still managed more negative plays with less games played.