That's because the final price post CSPA is almost always...

That's because the final price post CSPA is almost always the lowest price the SP reached that day. And if not it's only ever one step up from it.

For anyone accumulating that doesn't have buy orders already in, on a tee day, you'd be a fool to buy at any other time than after market close since the short sellers came in because they do a great job of driving the SP down late in afternoon and an even better job of stifling it or driving it down even further during pre-CSPA. Look at the historical data to see the pattern.

This is not financial advice. Do your own research. Review historical data for the daily highs and lows and final SP yourselves etc.