If the worth of a book were measured by the number of euphemisms employed to describe Mafia rubouts divided by the cover price, “Bummy Davis vs. Murder, Inc.” would be the literary steal of the year.

Two-bit hoods demonstrate they’ve got brains — by getting them splattered on fetid alley walls. Gangsters soar out of hotel windows (“The canary can sing, but he can’t fly”) and are described as firing bullets into one other’s craniums in more varieties than Baskin-Robbins has flavors.

Ron Ross’ gripping historical novel ostensibly depicts Brooklyn’s treacherous Brownsville neighborhood during the Depression era, and boxer Al “Bummy” Davis’ ascent to ring stardom and the exalted position of hometown hero. At times, however, the native New Yorker and former boxer dwells so heavily on the assembly line-like series of gangland killings that one is reminded of the ruthlessly Hobbesian PBS nature shows depicting life and death on the Serengeti, or, worse yet, insects.

Weak, sympathetic characters befriended by Davis are accorded the same treatment as amorous couples in slasher films. Life in Brownsville truly could be nasty, brutish and short.

It was a bit of all three for Davis — born Albert Abraham Davidoff — who was cut down at 25 breaking up a 1945 barroom robbery. Yet while few ever put Bummy on his back in the ring, the beloved boxer has been KOd by history.

The baby brother of two of the neighborhood’s most notorious racketeers, Bummy was tarred and feathered in the press as a mob-controlled lowlife. Not so, writes Ross, who spent the better part of a decade interviewing everyone from Bummy’s family to the guy who changed his motor oil before writing a biography that reads much more like a novel.

Ross’ Bummy acted as a big brother for a local mentally disabled man, turned down vast sums of money and put himself in danger by refusing to play ball with the mob, and beat up bullies as a child (and, admittedly, anyone else who looked at him funny).

Ross, who is described as a “former professional boxer, fight promoter and manager” on the book’s jacket, has obviously spent eons in the gym, and his rich descriptions of Brooklyn’s Jewish would-be champs pounding away at the heavy bag are all the better for it. The reader can close his eyes and feel he’s right there next to the bass-voiced, Yiddish-shouting coach and breathing in the pungent mixture of sweat and liniment. Ross is similarly on the money in his crackling descriptions of Davis’ many bouts, down to the champ’s snarling lip and ferocious, go-for-broke style.

While the author goes more than a bit overboard describing the antics of Brownsville’s death-dealing Jewish mobsters, he walks a fine line describing the frustrating plight of Davis, a fundamentally decent and honest man trying to claw his way to success in an impoverished, corrupt neighborhood during the nation’s most desperate era. This easily could have become a syrupy morality tale, but Ross’ Bummy is a mensch, not a saint.

A number of fellow reviewers describe Ross’ writing style as “Damon Runyon-esque.” I would say “Damon Runyon on steroids.” He also uses so much Yiddish that the book ought to come equipped with a built-in Leo Rosten.

Ross’ aggressive, street-smart style doesn’t always work, but, as another reviewer cleverly quipped, “So it’s overdone — you wanna make something of it?”

“Bummy Davis vs. Murder, Inc.” is a long-overdue redemption of a man slandered in life and death. Perhaps it will go a long way toward cleaning up the reputation of the most famous Brownsville boxer other than that fella who bit off a piece of Evander Holyfield’s ear.

“Bummy Davis vs. Murder, Inc.: The Rise and Fall of the Jewish Mafia and an Ill-Fated Prizefighter” by Ron Ross (418 pages, St. Martin’s Press, $26.95).