Knight is going through the roster again and making some edits just for the PS4 version. These edits will be available tomorrow is what I read and that's what everyone is talking about.
I'm sure the PS3 OSFM roster that's available now is fine but one extra day for some bonus edits is worth waiting for IMO.
It's not just edits for PS4, but re-rating players, adding in players etc. Various mistakes that weren't caught or just difference of opinion for player ratings. For instance I did the Cubs this year and I messed up Jorge Soler's age, that'll be fixed in the next update. People pick through the first OSFM release ever year for any tiny thing they can find, legitimate mistakes like putting a player at an incorrect position, or the wrong audio name. But often its differences in opinions "So and so should be rated higher...he's on my favorite team so fix that."
I don't think many people who play the show really dig in and get how players progress. For example since a player with a potential of 82 progresses slower than a player with 95 potential you can have cases where that 82 player has a higher starting overall rating than the 95 player. But over time the 95 player will progress well beyond that 82 player. But often the comments are "Blank is only rate a 68, while Blank is rate 71, that's bullshit!"
For PS4 its mostly just hair changes as one beard on PS3 might look just look a bit scruffy, but on PS4 its full on mountain man. Maybe if people notice that a minor league player has a Japanese-style or slap-style swing they can tell Knight to change the batting stance for that player.