Q. Why wouldn't CT% capture the HIT skill perfectly?
A. Because hitters swing at different pitches.
John Olerud routinely led the league in pitches taken. He only swung at pitches when he liked them. Who do you think is going to have a better contact rate -- a batter who only swings when he guesses right, or a batter who swings at everything?
Vlad Guerrero only walked 50 times a year, but his HIT ability was dialed way past 80, if there's a such a thing as past 80. The man could literally cover a pitch that bounced in front of him. And, true, that's reflected in a good CT%, but Vlad didn't lead the league in CT% or K%. He was swinging at balls outside the zone. Which brings us to:
Q. Does strength play into it?
A. Yes, if a batter takes a big swing, that drives his K% up and his CT% down. Year after year, the lowest K% batters are those who take a fungo swing at the ball.
Still, the fangraphs-style "ISO x K%" mostly accounts for this factor. The main reason that K% does not capture HIT, is because different hitters expand their strike zones differently. By HIT, the scouts refer to innate talent at squaring a baseball. That ain't the same thing as strikeout rate.
Q. So pitch selectivity makes your stats look good?
A. Sure. Picture Nick Collison playing college basketball, hitting 66% from the field. Why do you think that 2 out of 3 of his shots go in? Maybe it has a little something to do with the fact that he only shoots when it's a layup -- as John Olerud only swung when the ball was where he expected it to be on that particular pitch.
Picture Kevin Durant, on the other hand, driving down the right side, covered by two long defenders. He elevates when he hits the baseline and, falling out of bounds, swishes the three. Are you going to be able to compare Collison and Grant through field goal percentage?
The NBA scouts don't care whether Nick Collison scores 18 points on layups. They want to see one shot: the one where he's got 2 seconds on the shot clock and there's a 7-footer on him. That's a shot that will translate to the NBA.
Q. Which has exactly what to do with Jesus Montero?
A. The scouts don't care what Jesus Montero does with an 89 fastball out-and-over. They are watching him when he swings at a pitch that he will see in the American League.
Time and again, Jesus Montero takes vicious pitches, flicks the bat out and squares them up solidly. That's the HIT skill, the Edgar skill, and that's what the scouts are talking about.