How good is this defense?

[DrSpaceman]

I don't think the Colts played "trash" offenses this year.

But they played few of the top ones, at least in terms of QBs

I would say most would agree the list of top 10 QBs includes, no particular order, and we will exclude Luck :

1. Brees
2. Rodgers, though GB had an off year
3. Brady, grudgingly admitted
4. Raper-burger
5. Rivers this year was great, most years I would not put him on this list
6. Matt Ryan
7. Mahommes, new to the list this season
8. Brees
9. Russell Wilson
10. Jared Goff to round it out, especially given how good the offense has been

You may agree/disagree on a few, but 8/10 or so I would say most would agree on.

Colts have played exactly one of those 10 so far, and they lost, to brady.

now that was a strike shortened week and without Leonard and Walker too I think at LB, but still, a loss

Haven't faced any of the other 10 so far this year

After that there is a large group of middling to good, or up and coming QBs. Watson, Trubisky, Stafford, Wentz when healthy (and he is not), Cam Newton when healthy (again, not now), Dak Prescott, Eli, Kirk Cousins, some others. They have faced some of those and had success

Out of the top 10 or so for the year, besides Luck, though, did not have to face them this season, except Brady