I've got lots of very old Siberians - the dark cobalt blue "Caesar's Brother" and white counterpart "Snow Queen". In most cases, the crown is just below (an inch or so) the soil line. They should be upright, even at this time of the year when there's a bit of end of season yellowing. As a tall plant, you're going to get some leaf arching, but I've never known them to flop over.

You indicated it was a large clump. Would it be time for you to divide the clump? Has the clump grown to the point where the crown is now above the soil line? Usually every three years or so is a good division schedule to keep them from growing into a ring with an empty middle.

If it's a division issue, in zone 7 you should still have time to simply split and reset the new clumps and have them settle back in before a freeze. I don't split mine down into real small pieces, preferring to leave 8-12 fans per chunk.