SAN JOSE – When Mayor Chuck Reed’s office put out a news release boasting a staggering 70 percent decline in violent gang crimes since the start of the year, it raised eyebrows and expectedly drew the ire of the police union.

Union officials accused the mayor of cherry-picking numbers to gloss over spiking crime while the mayor maintained he was simply citing hard facts that temper what he considers a relentless union campaign to paint San Jose as increasingly unsafe.

The mayor’s release last week was the latest salvo in the intense political fight for the future of the Bay Area’s largest city, where the current City Hall administration and the police union have engaged in trench warfare for months. Crime is dominating city politics on an unprecedented level, framing the mayoral battle between Councilman Sam Liccardo, a Reed ally, and Supervisor Dave Cortese, who is backed by the union.

Longtime San Jose State political science professor and analyst Larry Gerston says residents and voters should take a fine-toothed comb to any bold numbers announced in such a heated political atmosphere.

“We have to be cautious about it,” said Gerston, who has observed San Jose for four decades. “I can’t tell you what’s true. The only time you’ll see heads or tails is after the outcome of the election.”

Meanwhile, the city continues to wrestle with a duality where the latest FBI statistics show San Jose has among the lowest crime rates for large U.S. cities, while, anecdotally at least, people who live here feel more unsafe than ever before.

For instance, violent crime dipped just over 10 percent in 2013 and jumped about 4 percent in the first six months of 2014. But most residents, Gerston said, are less likely to be victims of violent crimes than burglaries and car thefts.

“Home invasions and crimes like that are very personal,” Gerston said. “It’s like you’re violated. One of the oldest phrases around is, ‘Perception is reality.’ You can trot out all kinds of data, if people don’t feel right about it, it doesn’t matter.”

Property crime decreased 10 percent in 2013 and the first six months of 2014, according to crime data from the police department. But because 2012 saw a 10-year high, 2013 and the first half of 2014 still had the highest property crime rates of any other year in the last decade.

So in essence, the difference between the city’s two major political viewpoints on crime comes down to framing. Reed and his allies want residents to focus on the recent decreases. Opponents and the police union are emphasizing the long view, most recently in a political mailer where they cite figures showing increases in robberies, burglaries, and auto thefts of 12, 31 and 41 percent, respectively, from 2010 to 2013.

San Jose is not alone in seeing fluctuations, particularly the elevated property crime rate, which mirror larger trends in California, according to figures from the state Attorney General. Law-enforcement and civic leaders throughout the state have attributed the rise at least in part to realignment policies that allowed for early release for offenders convicted of certain nonviolent crimes – often property crimes – in response to court orders to relieve prison overcrowding. Many cities have also cut police staffing.

Still, figures from the FBI uniform crime report show San Jose has the lowest violent-crime rate among U.S. cities with more than 500,000 residents, and the sixth-lowest property-crime rate. For several years in the 2000s, San Jose was second only to New York City in property crimes per capita, a time when San Jose was routinely lauded as the safest large city in the country.

“If one of the reasons people live here is that it’s a safe city, and crimes against people go up, it might not be the worst city, but considering where it was, there are expectations,” Gerston said. “Unfortunately when you gain a reputation for something, it’s a lot easier to lose it.”

There are other reasons to approach those same numbers with skepticism, some provided by the source itself. SJPD found itself in controversy last year when it announced a decline in gang violence between 2012 and 2013, but did not immediately disclose that the figures were reached by different metrics, eventually acknowledging that the new stricter data standard accounted for at least some of the decrease.

In the case of the mayor’s pronouncement that violent gang crimes decreased 70 percent, his office arrived at that by comparing the numbers only from the month of January to the month of September rather than the first nine months of last year to the first nine months of this year. Comparing the stats for the nine month period of both years, the drop was closer to 15 percent.

Reed defended the analysis, citing data limitations he said prevented that kind of comparison, and said the larger point stands.

“I know it’s better,” Reed said of the gang-crime trends. “I’m not going to hide from the numbers. The department’s doing a good job, and should be recognized.”

Sgt. Jim Unland, president of the San Jose Police Officers’ Association, dismissed the 70-percent claim, and said residents’ safety concerns can’t be mollified simply by giving them crime figures that lack crucial context. He contends an exodus of officers – from 1,400 to just over 1,000 in six years – and the resulting lagging police response times have deflated residents to the point where they are reporting nonviolent crimes less frequently. Arrests have also dropped by half in the same timeframe.

“The public is smart enough not to buy it. After four years of police leaving in record numbers, increased 911 response times and violent crime continuing to rise, the citizens just want to feel safe again,” Unland said. “Their attempt to sell these ginned-up crime statistics won’t work.”

Reed said he can only work with what’s tangible.

“I’ve just got the data I’ve got. I have no way of knowing whether it’s underreported or not,” he said. “I have to focus on the facts and make sure people have access to the data.”

Mario Maciel, superintendent of the nationally esteemed Mayor’s Gang Prevention Task Force and one of the city’s foremost experts on gang violence, declined to comment on the 70-percent citation, instead lauding the city’s intervention programs while warning against overvaluing statistics about a complicated problem characterized by erratic violence.

“No matter what percentages are cited, the work is never done, it is cyclical. We can’t rest on our laurels on stats for any period of time,” Maciel said. “Percentage improvements today can be washed out in a weekend.”

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.