Hall of Famer Ted Williams wrote three books with Sports Illustrated writer John Underwood, and one of them was his memoir My Turn at Bat. I read it when it was first published in 1969 and when it was republished in 1988. I should have read another of their collaborations, 1970’s The Science of Hitting, because the absolute root of today’s power revolution is there on page 47.

Revolutions don’t happen immediately after their theories or mechanics are first pondered and enunciated. (Almost seven decades passed from The Communist Manifesto to the birth of the Soviet Union, but I didn’t say all revolutions are admirable.) In baseball revolutions often require decades to pass.

Williams contravened the entrenched wisdom of swinging “down” and called that swing dead flat wrong. Teddy Ballgame himself didn’t swing that way. If you look at him according to my concept of real batting average (RBA)—total bases, walks, intentional walks, sacrifices, and times hit by a pitch, divided by total plate appearances—he has the evidence of performance to back him up.

Do you think a man with a lifetime .482 on-base percentage (the highest in baseball history) and a lifetime 1.116 OPS (second highest) was talking through his chapeau? How about a man with the absolute highest RBA of any player the bulk of whose career came in the post-World War II/post-integration/night-ball era?

Player	PA	TB	BB	IBB	SAC	HBP	RBA
Ted Williams	9788	4884	2021	243	25	39	.737

“He advocated for what he described as a ‘slight upswing’ of about 10 degrees,” writes Wall Street Journal baseball writer Jared Diamond in Swing Kings: The Inside Story of Baseball’s Home Run Revolution. (New York: William Morrow; $28.99.)

His first reason for this was obvious: the only way to drive the ball, to hit a home run, is to hit the ball in the air. The other reason was a bit more subtle and insightful. Willams wrote that because pitchers are standing on a mound, by definition the flight of the ball will always be down. An upswing will put the bat “flush in line with the path of the ball for a longer period,” essentially giving hitters more margin for error. Modern hitting coaches, the leaders of the revolution, would call this “matching the plane of the pitch”—in other words, getting the barrel of the bat behind the ball as quickly as possible and swinging up through it, rather than swinging down to meet the flight of the ball.

Williams’s explanation of the upswing is accompanied by a diagram that shows the difference between the level stroke and the Williams stroke. It’s a simple sketch—just a white box, with the outline of arms, bats, and baseballs showing the value of the upswing. But that little graphic, buried in the middle of Ted Williams’s book, is perhaps the most significant visualisation of the swing ever produced. It inspired a revolution.

The revolution, Diamond writes, was delivered in due course by a cast of one-time players who couldn’t hit with a telephone pole when they did play the game at assorted amateur and lower professional levels. Or, whose skills vanished for various reasons. For assorted reasons, and from assorted starting points, they fell into post-playing lives during which they just had to know what they’d done wrong that younger siblings, friends, acquaintances could avoid doing wrong.

You know only too well the ancient saying about those who can doing and those who can’t teaching. But teachers have to do something first. They have to learn some things. Even if it involves learning what they did wrong before teaching someone else how to do things right. Even if they arrive in part from a few places you’d least expect to have baseball on the brain.

Mike Bryant devoured The Science of Hitting in his youth. He wasn’t talented enough to make it work for himself, but he could teach the Williams way to his son and his son’s friends. Another father he knew, Tony Gallo, former minor leaguer, was more than interested. He asked Bryant to teach his own son. Their sons made the Show, and those boys are rather splendid with the bat. You may have heard of them: Kris Bryant and Joey Gallo.

Craig Wallenbrock was a surfer dude turned food broker who once played college baseball and developed his own approach to the Williams philosophy by shooting and studying film over a decade before Hall of Famer Tony Gwynn made a fetish (and a nickname, Captain Video) out of it. The approach included studies of nature’s predators, karate, and samurai, applying their balances to the baseball swing.

When his own baseball coaches told him not to swing like Henry Aaron and others with classic power strokes, he asked why and was told those were freaks. Better to model yourself on someone like, say, Ron Fairly, a solid enough hitter but not exactly a game changer. By Wallenbrock’s coaches’ reasonings, Ted Williams was a freak, and so were Willie Mays, Mickey Mantle, Stan Musial, and Frank Robinson, among other such Hall of Famers.

“I’m thinking, let’s see—Ron Fairly, .260, not much power. Henry Aaron, 40 home runs,” he tells Diamond. “And I said, ‘Yeah but the freaks always seem to be the best players. So I want to study the freaks.”

One of Wallenbrock’s eventual disciples was Paul Konerko, the longtime White Sox first baseman. Another was a man he turned from nothing special as an Astro to never better after leaving the Astros—J.D. Martinez. Konerko may yet inspire a Hall of Fame debate; Martinez is one of baseball’s most feared hitters today. Wallenbrock’s analyses and observations took both players’ swings with too many moving parts, simplified them, and re-oriented them.

Richard Schenck taught high school, ran a tavern, raised baseball-loving sons, scoured the Internet for what was missing from his own college career (including sound coaching), shared his knowledge so contentiously he became a Twitter legend as a pariah as much as a prophet—and eventually turned Aaron Judge into a bit of a beast at the plate.

Doug Latta, at whose tiny facility Wallenbrock went to work applying his theories, was a swimming pool builder and former college player whose career was ruined by an ankle fracture. He created the near hole-in-the-wall Ball Yard facility, where major league hitters such as Chase Utley, Marlon Byrd, and Michael Young came to refine their swings. Latta suggested swinging up and staying back when asked. The line drives and periodic big flies started sailing off their bats regularly enough to put them on a timetable.

Wallenbrock, Schenck, Latta, and the other semi-underground hitting remodelers who reached (as hitting coaches) or influenced the game don’t all reference Williams by name, but they and their disciples are Teddy Ballgame’s grandchildren. Diamond not only tells their stories empathetically and in a user-friendly, panoramic prose style, he tells their thinkings and teachings without pedantry or condescension.

He also knows that for all Williams’s genius the man wasn’t a great teacher. It was one thing for Williams to break his own theory into a book but it was something else to teach it in person. Away from the printed page, man to men, Williams was better at conveying the mental approach to hitting than in communicating the mechanics. It took others, Diamond writes, “to take Williams’s ideas and figure out a way to explain them so that people could actually understand—to couple the upswing with the ability to pass it on to others.”

If you’re about to think that Swing Kings is just a long and winding defense of what’s been known as the launch angle since 2015 (when Statcast introduced it), don’t. The very mention of launch angle drives critics either to drink or to attempted murder, but Diamond and the Swing Kings each would remind you that chasing launch angle alone is as hazardous to a hitter’s health as seeing nothing but launch angle in a swing is to coaches.

[S]imply chasing “launch angle” without a full understanding of how to do it is a good way to ruin a swing. After stories about [Justin] Turner’s and Martinez’s surges rocked the baseball landscape, plenty of hitters attempted to mimic their success by changing their swings to improve their launch angle—almost always without the assistance of an outside coach. Most saw their performance decline.

It’s for that reason that most of the renowned “Swing Kings” avoid talking about launch angle at all, creating a lovely bit of irony: the people most often thought of as disciples of launch angle don’t actually use the term . . . to describe what they do . . . Martinez, a hitter who understands a thing or two about the swing, said, “People don’t understand—they just say ‘launch angle swings’ without breaking down and understanding what they are and what they do’.”

The one thing the Swing Kings couldn’t always re-align with their disciples, alas, was the thing that Ted Williams knew was just as important to a genuinely great hitter were as the physics and mechanics of the craft. The Science of Hitting includes a chapter called “Three Rules to Hit By”—1) Get a good ball to hit. 2) Proper thinking. (Have you done your homework? What’s this guy’s best pitch? What did he get you out on last time?) 3) Be quick with the bat.

There are reasons why strikeouts climbed concurrent to home runs the last few years. Even the best of the Swing Kings’ disciples strike out too often, and on pitches they had little business trying to hit in the first place. There’s no disgrace in working out the base on balls if you don’t see a pitch you can nail no questions asked. The Swing Kings’ students’ discipline in refining their swings hasn’t always meant stronger plate discipline. (J.D. Martinez has almost a 3-1 strikeout-to-walk rate per 162 games; Aaron Judge: 2-to-1.)

“A good hitter,” Williams wrote, “can hit a pitch that is over the plate three times better than a great hitter with a questionable ball in a tough spot. Pitchers still make enough mistakes to give you some in your happy zone. But the greatest hitter living can’t hit bad balls good.” (In other words, among other things, Hall of Famers Yogi Berra and Joe Medwick—two guys who could send pitches outside their ZIP codes for base hits or over the fence—were outliers.)

Not everything you do hit for a solid line drive or a climbing fly ball is going to land for hits, bound off the fence, or fly into the seats. On the other hand, which would you really prefer: a batter striking out a little too much, or a batter hitting into a few too many double plays?