My experience is that pre-lagering the astringency IS enough to be objectionable; post-lagering it is no longer objectionable (or even discernible for that matter). One experience I had that illustrated how much astringency can be produced in decoction mashing was a traditional, triple-decocted bock I did - prior to this I would not have thought this was possible.
After kegging the bock and carbonating over a few days, I pulled a sample and was heart-broken at the astringent quality that kicked me in the face - so much so that I almost dumped the batch there and then because there was no way this one would ever clean up (or so I thought). However, since I had plenty of empty kegs and batches that could precede this one, I decided to let it lager for many weeks (eight if I recall correctly) at ~38-40F. After the lagering period, I pulled another sample and it was 180° turnaround! No astringency, and a classic traditional bock character. After experiencing this turnaround it flashed me back to something Noonan wrote about in New Brewing Lager Beer which basically said exactly that: Lagering will precipitate the astringency in lagers as part of the process (or something like that).
This is very interesting, and I've seen the same thing in a parallel universe.......
Recently I discovered that either the carbonation or the corn syrup, or both, in soda pop do not agree very well with my digestive system. Therefore, I decided to change over to a new soft drink of choice: ICED TEA. I drink a ton of this stuff at work everyday, instead of the old standby of Coke, for those times of day when I can't drink beer or cider, etc. So anyway...
Of course I brew my own iced tea. I make a gallon at a time usually, then bring the whole jug to work. Anyway... I have noticed that the first day or two after making it, it's got some extra zing to it, no doubt the tannins that are still in suspension. However this very quickly falls away over about 36-48 hours, after which it is a very smooth and easy drinking beverage. And I actually kind of like the fresh taste as well. But I definitely do notice a difference after the tea has sat in the refrigerator to "lager" for a couple days. This was not on purpose but discovered by accident.
My point is, tea has a lot of tannins, as many of us have heard. And yes, after brewing and drinking dozens of gallons of the stuff over recent months, I definitely can tell that the tannins do mellow after "lagering" for a few days. Fascinating that this correlates against lagering of, well, lager beer. Awesome.