Outside of four teams (UNL, Wis, Hawaii, and Minne), no one is averaging 4K. Only the top 10 average over 3K. So aiming for an average of 2 to 2.5K, is more than reasonable with expectations of 3-5K for big games. Pitt was 43rd nationally in attendance last year with 1,140 per match, but that was third in the ACC behind UNC and Clemson and behind the conference averages of the B10, Pac, B12, Big West, and SEC. This year Pitt averaged 1,113 (not counting the NCAA games, but including OSU at PPG Paints). So it does appear to be down even with the massive PSU crowd.
I was talking peak attendance not average. We weren't all that far behind PSU last weekend, but they aren't hosting their games in a 12K seat arena like we are. Clearly Pitt holds it there because they think it is a nicer, more appealing building for fans and it holds more people. If you aren't going to need 3,000+ seats, then there's nothing stopping them from having it at the FFH now. Clearly they were anticipating the Pete being an advantage in receiving the Regional but they were wrong.
As far as your attendance numbers, I give very little credence to anything Pitt reports. I am just stating that after attending the majority of matches, I thought it was a healthy crowd this year. They do have some issues like the opening weekend afternoon games and I highly doubt anybody showed up to the OSU match at PPG.
I will relay my experience being in town and going to the UL game before Thanksgiving. There was only one ticket window open (at the top of the Pete) and a long 15-20 minute line outside in the cold to get tickets from that window (and it would have been longer if some people weren't passing out their extras for free). There were also no signs at the main entrance of the Pete about tickets and that led to some confusion by those entering from the lower campus side going through security, who then had to go back out and up to the top and outside to wait in the long line. Many in the ticket line were late to the start because of the wait time to the window.
This is why I argued on the BB board that the conventional wisdom of nobody buying single game tickets is a myth. VB is almost solely single game tickets.