By choosing Senator Vance of Ohio, President Trump has thrown the conventional wisdom playbook for running mates out the window. Refusing to sit on a lead, he’s following the dictum of the NFL coaching legend, John Madden: “All a prevent defense does is prevent you from winning.”

Mr. Vance checks few boxes on the standard vice-presidential wish list. Yet in drafting the newcomer over safer picks, Trump signals that he wants a brawler who’ll hit the line hard and carry the ball into Democratic territory.

“The vice president can’t help you,” President Nixon said during his second White House run in 1968. “He can only hurt you.” It’s a defensive posture that Trump rejected, even knowing that Mr. Vance’s past criticism provides Democrats plenty of devastating hits.

In 2016, Mr. Vance called Trump “cultural heroin,” an “idiot,” and a “reprehensible” man “leading the white working class to a very dark place.” He even proclaimed himself a “Never Trumper guy.” Then a private citizen and best-selling author, he branded Trump “America’s Hitler.”

It’s the kind of rhetoric that Republicans are objecting to in the wake of Saturday’s assassination attempt, and Mr. Vance’s selection undermines that messaging. Plus, in his memoir, “Hillbilly Elegy,” he criticized the “message of the right” and the “cultural movement in the white working class to blame problems on society or the government.”

These stiff arms against MAGA doctrine would have been enough to sink him with President Wilson, who loved to hold a grudge. Yet while Trump’s judgments are binary — “loyal” or “disloyal,” “fighter” or “weak” — they’re also subject to change.

Trump is always open to political players earning a spot on his roster. A running back who suits up for the opposing team on any given Sunday is welcome, to quote a word from Trump’s Truth Social post announcing Mr. Vance, to bring his “talents” to Team Trump.

Mr. Vance has, since his election 2022, transformed into a staunch Trump supporter. Yet since he’s served only just less than two years in the Senate and has little legislative baggage, expect his past remarks to loom large in Democratic attacks. 

Trump has forgiven Mr. Vance’s trash talk even if Democrats will see that it’s not forgotten. “J.D. will continue to fight for our Constitution,” Trump wrote of the Marine Corps veteran, “stand with our troops, and will do everything he can to help me MAKE AMERICA GREAT AGAIN.”

Mr. Vance was “the person best suited to assume the position,” Trump said. He “graduated from Ohio State University in two years, Summa Cum Laude, and is a Yale Law School Graduate” with “a very successful business career in Technology and Finance.” 

The ideal vice president, the strategists say, delivers a state or demographic. Mr. Vance is Scotch-Irish and represents the Buckeye State, which Mr. Trump won in 2016 and 2020 and where he has led President Biden by about ten points in the Real Clear Politics average for months.

Ohio does offer good political geography, orbiting swing states that Trump namechecked on Truth. Mr. Vance, he wrote, “will be strongly focused on the people he fought so brilliantly for, the American Workers and Farmers in Pennsylvania, Michigan, Wisconsin, Ohio, Minnesota, and far beyond.”

Mr. Vance also adds youth. He’s 39, just four years older than the constitutional minimum of 35 years and the same age at which Nixon was elected with President Eisenhower in 1952. Ike himself was 62. Trump, 77, also found a contrast to his stable urban rearing in Mr. Vance’s compelling story of overcoming a dysfunctional home.    

Trump, in the same way he recognizes real estate with potential, also sees what coaches call “intangibles” in Mr. Vance, which may already have paid big dividends. Elon Musk, a supporter of the Ohioan, pledged to give $45 million a month to the pro-Trump America PAC after his selection.

For three presidential election cycles, Trump has played the game in ways political coaches say a candidate cannot. America will see if rewriting the playbook yet again with a foe-turned-friend runs up the score on Mr. Biden or ends up being a fumble just yards from the goal line.