This morning, I was playing around with some of our plate discipline calculations. I really like the metrics we have for measuring a player’s approach at the plate, but because they are broad categories that combine numerous variables into one number, there are some questions that none of them answer all that well on their own. For instance, if you just wanted to know who the most unrepentant hacker in 2014 has been, you could simply sort the leaderboards by Swing%, and you’d see Chris Johnson at the very top, swinging at a higher rate of pitches (57.1%) than anyone else in baseball.

But knowing that Johnson has swung at the highest percentage of pitches doesn’t really make him the game’s most aggressive hitter, as part of his high swing rate is that he’s been thrown an above average number of strikes. Pablo Sandoval is right behind Johnson in overall swing rate, but his Zone% is 11 percentage points lower than Johnson’s, so he’s getting far fewer pitches to hit but still chasing the same amount. By any reasonable measure of hackiness, one would have to conclude that Sandoval has been more aggressive than Johnson.

Of course, we have a measure of swings at out-of-zone pitches, which is a pretty good way to measure which players fit the hacker mold. However, by O-Swing%, Matt Adams ranks #2 in baseball, but his overall swing rate only ranks 17th. Is he one of the game’s most deliberate free swingers, or does he just struggle to recognize balls from strikes?

When I think about the hacker label for a hitter, I think of guys who swing as if they had made up their mind before the pitcher even started his delivery. Location and pitch type are secondary to the desire to just put the bat on the ball, and they won’t be deterred from swinging no matter what the pitcher does. So, I thought that perhaps we could better identify those types of hitters by looking at a ratio of two of our plate discipline stats, and so out of curiosity, I divided Swing% by Zone% to get a ratio of swings-per-balls-in-the-zone. Others have created far more complex and mathematically sound formulas to get at the same idea, but there’s value in ease of calculation, so I was curious how Swings Per In-Zone Pitch would do.

From 2008 to 2014, here are the five leaders in highest Swing/Zone.

If you were looking for a measure of hackiness to pass the smell test, you probably couldn’t ask for a better top five. Vladimir Guerrero kind of defined the unrepentant hacker model, while Sandoval and Hamilton best embody his spirit among today’s active players. Both Soriano and Pierzynski have had long careers despite an apparent desire to walk as rarely as humanly possible. This is basically the who’s-who of what I would consider the game’s biggest hacks over the last five or six years.

And it’s not just these five. Two of the next three on the list are Delmon Young and Jeff Francoeur, both of whom had potentially promising careers essentially ruined by an inability to control the strike zone. Both were top prospects who busted because they just couldn’t stop hacking at pitches that their opponents wanted them to chase.

But in that group of three, tied for the sixth spot on the list overall, is a name that gives me pause about this measure. It’s a name that I would not have expected to find: Freddie Freeman. Putting him in this group is like playing a very obvious game of “which of these is not like the others?” For reference, here are the 2008-2014 walk and strikeout rates for the top eight players by this Swing/Zone measure.

Freeman has the highest walk rate of the group, and while his strikeout rate is higher than most of the rest, he’s also played his entire career in the era of quickly rising strikeout rates, and has done so at a very young age. Additionally, his strikeout rate has been trending downwards since entering the league, and at just 18% this year, below the league average. At 12%, his walk rate is also a career best, and his current profile looks nothing like that of guys like Guerrero, Sandoval, or Hamilton.

But the reality is that even as Freeman has improved, his ratio of swings per pitch in the zone is basically stable.

This isn’t a case where Freeman’s career numbers are skewing the data. Even as he’s matured, and his walk and strikeouts rates have improved, he’s maintained a swing/zone ratio in line right in line with the career marks of Delmon Young and Jeff Francoeur.

Of course, this gets back to the fact that swing percentage is a pretty large bucket, and not all swings are created equal. The key difference for Freeman versus the guys who fit the unrepentant hacker model? Freeman’s swings are heavily slanted towards pitches in the zone. Again, those same eight players, but now, there O-Swing% and Z-Swing%.

Name O-Swing% Z-Swing% Z-Swing/O-Swing Freddie Freeman 33% 77% 2.32 Josh Hamilton 39% 78% 2.00 Delmon Young 42% 75% 1.82 Jeff Francoeur 41% 74% 1.81 Pablo Sandoval 44% 76% 1.74 Vladimir Guerrero 46% 79% 1.73 Alfonso Soriano 41% 68% 1.68 A.J. Pierzynski 44% 73% 1.68

Freeman swings at basically the same number of strikes as guys like Hamilton and Guerrero, but a much lower percentage of balls. If you challenge him, he’s going after it, but he doesn’t chase bad pitches to nearly the same degree of the other guys on the list. And so, instead of being a busted prospect who never walks, Freeman has developed into one of the game’s best hitters. He’s not a particularly patient hitter, and he’s getting walks more out of pitcher fear than working the count, but he’s at least willing to not expand the zone to a ridiculous degree.

Really, Freddie Freeman isn’t a hacker, even if dividing Swing% by Zone% makes him look like one. This is more of an example of why that’s not a perfect measure of hackiness, but I also found it interesting, because I haven’t watched Freeman enough to pick up on just how often he swings at pitches in the zone. He’s certainly an aggressive hitter, but if you’re going to be aggressive, be aggressive in the way that Freddie Freeman is aggressive.