Stats tell me what happened and, believe it or not, give me a clearer understanding of what might happen.
Seriously, I make my roster decisions based on ratings. But, at some point during the season, I'm going to play the guy hitting .300 over the guy hitting .240 regardless of ratings. It may be luck. It may be randomly generated results. It may be me misunderstanding what works in my park. But I'll be damned if I sit on my thumbs and say "But he has better ratings" while I lose games.
That's the difference between people with losing records and winning records. Failure to adjust your thinking simply equals failure.