I completely agree, 2013-2015 his cap number corresponded very fairly to his quality as a QB. It was not the problem back then and not once did I complain about it.
From 2016, however, he is one the highest paid QBs. Unfortunately, he is not playing even as a top 10 QB. If he was, I would not complain. Or, if his cap hit ranked around 15th among QBs (which would still be pretty generous), i.e. he'd get 18-19M, I would not complain either. It would open up enough cap space so we could afford not losing some of our key FAs. Instead, he's soon to be the top paid QB, but in spite of that needs a lot of help from his teammates to be adequate. We can not afford that, though, one of the biggest reasons for that is Flacco's contract.
Of course it was just one year under his enormous cap number. Who knows, he might be the league's MVP next year and justify his contract. I really really hope so. But if he doesn't and has another below average season, it'll be interesting to hear what the FO has to say about him.
I also agree with you that this probably would not be an issue, if we would have been able to draft better, especially in the early rounds and especially on offense. But we haven't. This is the other major reason why, in my opinion, we are in such a crappy spot right now. And I've called out the FO on these boards many times for it. In fact, most of our recent early round draft picks have been some of the biggest busts in the league. And the few truly great early round picks we manage to find we can't keep, because we don't have the cap room.