The families of two slain New York City police officers threw out the ceremonial first pitch at the Mets' home opener at Citi Field, while the widow of American Sniper Chris Kyle pitched in for the San Diego Padres. New England Patriots quarterback Tom Brady also threw a first pitch, at Fenway Park in Boston - but didn't do himself proud, chucking the ball straight at the ground. The NYPD families were joined by Mayor Bill de Blasio at a time when his relationship with the police department is again coming under scrutiny. Scroll down for video . New York Mayor Bill de Blasio waves as he stands with members of the families of New York City Police Detectives Wenjian Liu and Rafael Ramos before they threw out the ceremonial first pitch at the Mets home opener baseball game against the Philadelphia Phillies in New York . Members of the family of New York City Police officers Wenjian Liu and Rafael Ramos throw out the ceremonial first pitches before the Mets opening day baseball game . An American flag is displayed before the baseball game between the New York Mets and the Philadelphia Phillies at Citi Field . New York City Police Detectives Wenjian Liu and Rafael Ramos are honored on a giant video screen before the start of the New York Mets home opening day baseball game . Police officers hold a giant American flag before the baseball game between the New York Mets and the Philadelphia Phillies . Tribute: New York Police Department helicopters fly over Citi Field on Monday . Widow of 'American Sniper' Chris Kyle, Taya Kyle, center,  throws out the first ceremonial pitch on Military Opening Day before a baseball game between the San Diego Padres and the San Francisco Giants in San Diego . Taya Kyle gets a hug from San Diego Padres starting pitcher Andrew Cashner after throwing out the first ceremonial pitch . De Blasio's relations with the police unions and some rank-and-file officers were fractured in the aftermath of the December shooting that claimed the lives of Officers Rafael Ramos and Wenjian Liu. They were murdered on patrol in Brooklyn on December 20 by a crazed gunman who then committed suicide. Since that crisis, which threatened to overwhelm the mayor's agenda, de Blasio has taken pains to repair relations with the nation's largest police force, brokering a new union contract, investing in new technology and training, and doubling down on his public praise of the department. On Monday, he joined the tens of thousands of fans in cheering as the officers' images were displayed on the park's giant video screens and again when Ramos' two sons and Liu's widow threw out the pitches to Mets players David Wright, Matt Harvey and Curtis Granderson. De Blasio, however, was largely booed when he was introduced to the crowd. A year ago, de Blasio was also booed as he threw out the first pitch (a strike). Both years, he sported a Mets cap and jersey, which was emblazoned with his last name and the number 6, a tribute to Rico Petrocelli, a longtime shortstop on de Blasio's favorite team, the Boston Red Sox. Petrocelli, like de Blasio, was also of Italian descent and lived in Brooklyn. The tribute to the NYPD comes as de Blasio is weighing a City Council proposal to hire 1,000 more police officers. The idea has been endorsed by union leaders who said it would reduce pressure on existing officers to keep crime low. But de Blasio rejected an identical council proposal a year ago, pointing to the city's record low crime and suggesting that the money would be better spent elsewhere. Members of the Liu and Ramos families are greeted by New York Mets' Matt Harvey, left, David Wright, fourth from left, and Curtis Granderson, right, after throwing out the ceremonial first pitch . Members of the Liu and Ramos families, including Yenjian Liu's widow, Pei Xia Chen, second from left, throw out the ceremonial first pitch . Police Commissioner William Bratton has, at times, signaled support for the effort to hire more officers for the department, which now has a headcount of about 34,500, about 6,000 fewer than at its peak in 2001. De Blasio has not committed to hiring more officers but has been more receptive to the proposal in his public remarks than he was a year ago. The council's budget office projected that hiring two new classes of officers, to total 1,000, would cost nearly $69m in the upcoming fiscal year. But the council believes that the cost will be offset by the corresponding reduction in overtime. New England Patriots quarterback Tom Brady threw out a ceremonial first pitch at Fenway Park for the Red Sox . Oops: Brad throws the ball straight into the ground, despite being a distinguished quarter-back . Brady hugs David Ortiz of the Boston Red sox after throwing out a ceremonial first pitch . Brady talks with  Nancy Frates, Julie Frates and Pete Frates on Opening Day at Fenway Park . Though the city's overall crime rate has fallen again, murders are up nearly 12 per cent from this time a year ago, and shootings have also increased, according to NYPD crime statistics. The mayor is expected to offer a counter-proposal next month and a budget deal must be completed by the end of June. Meanwhile, in Boston, New England Patriots quarterback Tom Brady threw out a ceremonial first pitch  at Fenway Park for the Red Sox. However, the legendary NFL player threw the ball straight into the ground.at the batter's box. In San Diego the widow of 'American Sniper' Chris Kyle, Taya Kyle, center, threw out the first ceremonial pitch on Military Opening Day before a baseball game between the San Diego Padres and the San Francisco Giants. Brady takes batting practice with former Boston Red Sox pitcher Pedro Martinez after throwing out a ceremonial first pitch . Brady acknowledges the crowd while holding the 2014 Viince Lombardi trophy during a ceremony honoring the 2015 Super Bowl Champions . Winners: Brady poses for a photograph with Ortiz  in the batting cage .
Rafael Ramos and Wenjian Liu were murdered on patrol in December .
Their families threw out the ceremonial first pitch at the Mets' home opener .
They were joined by Mayor De Blasio, who was booed when introduced .
Tom Brady and 'American Sniper' widow Tara Kyle also threw first pitches .