Has Brad done anything wrong in your eyes?
I'm not Jon but I'll give my opinion. I don't think there have been any glaring mistakes and hindsight is 20-20. There are things I didn't care for at the time, namely trading up to draft Brodrick Martin and Isaac TeSlaa. I'm sure there are more but I can't think of any off the top of my head.
I know you wanted them to trade for a top edge rusher and I disagree because of the cost in picks and salary cap concerns. You thought they should go for it. We will never agree and that's fine. I don't see a point in beating the dead horse again.
In general there are things he could have done but Holmes values keeping his young core more than trading for or signing an expensive player. I agree with it and you didn't and that's fine. We will never agree on anything. There may be a time in the future when I would agree with going for it but I didn't last year.
Holmes is building his team through the draft and wants to keep the young core together. I don't see him signing expensive free agents or trading high picks for one.
EDIT TO ADD: I think he should have added an edge in the draft or in free agency. I didn't mind him resigning Davenport because his guarantee was just a little more than the veteran's minimum but I think he should have signed another one for depth. I think he would have signed Za'Darius Smith but I honestly think he saw that his heart wasn't in it. I think that's more of a reason for his subpar play than anything physical.