Here's one thing I know.
Batters got more hits per 9 against Carlton than Hunter.
Batters walked more often per than against Carlton than Hunter.
Seems like Carlton did a better job at keeping the ball in the park but wasn't quite as adept at giving up less hits/walks. IOW, when a batter got a good piece of Hunter's pitches, it went a long way. They just didn't hit they ball as well, as frequently, against Hunter. And Carlton didn't quite control the strike zone.