I agree with WOY's assessment, particular the point that he's a full run at this point, not how he'd look, I think, if he was diving back to a base. I'm curious about the angle of the base. Were the bases anchored in 1975? I'm thinking they were, so the bag's angle looks a tiny bit off. One commenter did note that Rose went from first to third twice in the August 27th game.
So here's my take on a Rose slide that I did way back when.