I agree with several previous posts, as it looks like they're pretty accurate on the modern 'shiny' stuff and I believe they get the Poor to Good (1-2 range) stuff graded correctly, but the 4-8 range stuff is really off.
I have an order of 1950's to 70's mid to higher grade cards on their way back to me right now from PSA and every single card is at least 1 grade lower (a couple are 2+ grades lower) than I've been accustomed to over the past 22 years. It seems to me that they take an even harsher grading approach to a card that is even slightly off-center. These new graders are so used to seeing perfectly centered new cards, that 40/60 off center vintage cards are getting hammered.....and it seems that they don't realize vintage cards were manufactured with rougher non-perfect cuts, as compared to modern. It would be great to see different graders for only modern OR only vintage, as mentioned.
Knowing this, I'll just stockpile cards for now and see if anything changes in the future.... and I'll patiently wait each month for their 'We Agree We Brutally Undergraded Everyone's 2021-22 Vintage Card Submissions and Would Like to Fix It Monthly Special'....That'll be the day, LOL
