There is defiantly some funny business going on in MyTeam on PC. I had just got enough free time again to play and oh boy, just search the AH for diamond or amethyst players and you'll see a ton of of the same player with the exact same bid, buyout and time left on the auction. Not to mention the same shoe and contracts as well. I mentioned this to 2K support and they told me it was just multiple users posting the same card around the same time which is obvious not whats happening. Here's a sample of what I saw a few days ago:
I bought the PS4 Version for the first time ever so I can enjoy the multiplayer modes. Shame 2K doesn't seem to care about people effecting MyTeam and other online multiplayer modes on the PC.