That's not where the bump came from.
DVOA would be NEGATIVELY impacted from feasting on bad offenses. That's the point of it.
DVOA doesn't adjust for strength of opponents. Not in the way you suggest. You don't get less "points" for a 10 yard pass vs the Jets than you would vs the Bucs. Unless the Bucs give up very few 10 yard passes and the Jet's give up lots. And those stats are effected by who those teams play.
FO explain it here,
"The biggest variable in football is the fact that each team plays a different schedule against teams of disparate quality. By adjusting each play based on the opposing defense’s average success in stopping that type of play over the course of a season, we get DVOA, or Defense-adjusted Value Over Average. Rushing and passing plays are adjusted based on down and location on the field; passing plays are also adjusted based on how the defense performs against passes to running backs, tight ends, or wide receivers. Defenses are adjusted based on the average success of the
offenses they are facing. (Yes, technically the defensive stats are actually “offense-adjusted.” If it seems weird, think of the “D” in “DVOA” as standing for “opponent-Dependent” or something.)"
So as you see here "Defenses are adjusted based on the average success of the
offenses they are facing" which really all depends on who your opponents are facing.
So let's say for example we play the Cowboys and the Cowboys are averaging 30+ points a game with Dak playing some poor teams in a poor division, but then Dak is out and they only put up 10 (with all the yardage and play stats that go along with a poor performance) then you're going to get a whopping DVOA boost.
How many backup QB's alone did we face last year?
Like I said, the D was better but we didn't have the 10th best D in football in reality. All DVOA says is we had the 10th best D vs the opponents we played based on how those teams played against their other opponents, without factoring if they had a backup QB starting, their star WR or RB missing etc
I'm not trashing DVOA and it's far more complicated than described above factoring alot of variables but like every system in existence it's not perfect. It still has a lot of value.
At least, that's how I understand it from reading their explanation.