I'll give you a quick example of why I need the numerical rating: Mike Yastrzemski, Carl's grandson.
Mike is in his rookie season and his season started late. He's only played about 1/3 of a season. He's hitting .259.
But he has an OPS of .787 (thanks to a .487 SLG, showing power) and an OPS+ of 105, so about 5% better than average.
He has a bWAR of 1.0, which appears to be about half due to his defense. That would extrapolate to a 3.0 WAR for a full season.
I haven't seen Mike play an inning, but these numbers show he's been playing as a solid, above-average major league outfielder.