The “lost memoir” of Lou Gehrig is like a bowl of lukewarm oatmeal. It can fortify innocent youths, and it might soothe cranky dyspeptics. But it is bland mush.

The famously modest, upright first baseman for the New York Yankees offers advice for young ballplayers: Get your sleep and exercise, learn from the veterans, treat coaches and umpires with respect.

His mother is his best friend. His teammates support each other. His fellow baseball stars are swell guys — even the belligerent, hot-tempered Ty Cobb.

“There will always be great ballplayers so long as kids can find sandlots on which to mark off a diamond,” proclaims Gehrig, “and baseball can never grow less honorable so long as those same kids look to the big league stars as their heroes.” Some of the worst baseball writing over the past century and a half has trafficked in such sentimentality, casting athletes as exemplars of character. Gehrig’s account is full of such goop.

In Gehrig’s defense, he was not writing for posterity. In the summer of 1927, he signed with the Christy Walsh Syndicate, which provided ghostwriters for star athletes and coaches, including Cobb, Knute Rockne, Walter Johnson, Pop Warner and Gehrig’s superstar teammate Babe Ruth. Gehrig consulted with his own ghostwriter for a series of newspaper columns about his life and career.

At that point, the 24-year-old Gehrig was a legend in the making. During the 1927 season he hit 47 home runs, batted .373 and drove in 173 runs. Led by its “Murderers Row” of power hitters, the Yankees won 110 games and swept the Pittsburgh Pirates in the World Series. Over the final months of the season, Gehrig’s string of 30 ghostwritten articles appeared in the Oakland Tribune, Pittsburgh Press and Ottawa Daily Citizen.

Because the articles did not appear in prominent newspapers, they escaped the attention of Gehrig’s previous biographers. Author Alan Gaff, while researching another topic, unearthed the series. Shaping the columns into coherent chapters, he has fashioned a thin memoir for Gehrig and added a brisk biographical essay.

Gaff’s discovery offers a glance at Gehrig as he burst into the American consciousness at the height of the Roaring Twenties. He was not yet the “Iron Horse” whose 2,130 consecutive game streak would carry him to the end of his career in 1939, establishing him as an icon of steadfast reliability throughout the Great Depression. He had yet to contract amyotrophic lateral sclerosis, the debilitating affliction that most now call Lou Gehrig’s disease. Gary Cooper had yet to portray him in the classic 1942 film “The Pride of the Yankees.”

But the memoir offers little insight into Gehrig. Jonathan Eig’s top-notch biography “Luckiest Man: The Life and Death of Lou Gehrig” depicts its subject as fundamentally decent and resolute but also plagued by self-doubt and flustered by celebrity. By contrast, Gehrig’s ghostwritten account stays at the surface, coating the sport in myth.

“Baseball is a great game, and worthy of the greatest and best men who ever played it,” declares Gehrig. He seeks to paint the sport as respectable, countering the critics who think of ballplayers as “roughnecks and ingrates and ne’er do wells.” He describes his teammates as serious, professional men who practice good sportsmanship. They are relatable people with regular lives, “the same as the doctor or the lawyer or the clerk.”

Babe Ruth plays a starring role in Gehrig’s story — the serialized articles ran under the title “Following the Babe.” In 1927 the two Yankee sluggers, batting third and fourth in the lineup, had a much-ballyhooed race for the home run title. Ruth triumphed, bashing a record 60 home runs. The public grew fascinated not only with their titanic blasts but with the contrast between the humble Gehrig and the attention-grabbing, hard-living, free-swinging Babe.

Gehrig casts Ruth as a jocular, bighearted mentor who lends good advice on batting, health and even personal finance. He is happy when Ruth wins their home run duel, and he professes that they are not rivals: “There is just one Babe. He stands alone and incomparable.”

It is not that the “lost memoir” misrepresents Gehrig. He genuinely liked his fellow players, took pride in his professional discipline and enjoyed an unlikely friendship with Ruth. He possessed a real sweetness — he calls his mother “the greatest pal I ever had.”

Still, it behooved Christy Walsh’s ghostwriter to amplify these traits. The journalists of the 1920s were creating new types of sports celebrities, forging heroes that embodied marketable values. The Columbia-educated Gehrig was the perfect vehicle to sell baseball to consumers of the burgeoning middle class. When he polished the image of the blissfully sinful Babe, he lined the pocketbook of Walsh, who was Ruth’s agent and business manager. And while Gehrig adored his mother, he also suppressed his resentments about her smothering nature, since that was not promotional material for young baseball fans.

In his introduction and biographical essay, Gaff fails to probe how and why ghostwriting journalists crafted these popular columns. Instead he offers unsubstantiated reassurances about the authenticity of Gehrig’s tale. “No matter who wrote down the words,” writes Gaff, “there is no doubt that Lou’s memoir came directly from the heart.” That naive slushiness belongs in the 1920s, not the 2020s.

Lou Gehrig

The Lost Memoir

By Alan D. Gaff

Simon & Schuster. 230 pp. $26