All-Star MVP Melky Cabrera, right, of the San Francisco Giants, celebrates his two-run, fourth-inning home run with the Cardinals’ Matt Holliday. Cabrera helped the NL to an 8-0 rout of the AL in the All-Star game on Tuesday, July 10, 2012, in Kansas City, Mo.

Kansas City, Mo. ? The sound of the sweet spot of a baseball bat crushing a baseball was fouled by a backfire that could be heard from here to San Francisco and back Tuesday night in the top of the fourth inning of the All-Star game won by the National League, 8-0.

Poor Royals.

Anybody who’s anybody in major-league baseball convened at the beautiful baseball stadium in the middle of nowhere, instead of the middle of downtown, where it should be located, and everyone in baseball had to be reminded of what a lousy trade the Royals made in the offseason.

So far, Melky Cabrera and a few others directly or indirectly involved in the November trade have made it backfire repeatedly, never quite so loudly as when Cabrera played a central role in the beating administered by the visitors, never so loudly as when he received All-Star game MVP honors.

Cabrera, 27, had the first hit of the game with a first-inning single in his first (of many) All-Star at-bat and scored the game’s first (of many) run. In the fourth, he received a decent showing of support from jilted Royals fans when he tore into Texas Rangers left-hander Matt Harrison’s offering and parked it in the home bullpen behind the left-field fence, a two-run homer.

No less an authority than National League manager Tony La Russa said of him, “Melky, last year, this year, he’s as good a hitter as there is in either league.”

And the Royals gave him away for a return that so far has made them worse than they would have been had he been given away for nothing.

Cabrera, with his fourth team in four seasons, said words that made it seem as if the trade from the Royals didn’t hurt, but his pained expression when asked about it betrayed those words.

“You have to be mentally ready and physically ready for those decisions you have no control over,” Cabrera said through an interpreter. “It was a business decision that the Royals traded me. San Francisco is my new team, and I’m very happy to be there.”

The feeling is mutual. Six fans dress as milk men for every home game. He’s a cult hero already. He could have been one in Kansas City. Cabrera had 201 hits for the Royals last season, ripped 44 doubles, hit 18 home runs, scored 102 runs and drove in 87.

San Francisco Giants general manager Brian Sabean has a habit of making the right moves at the right time. Based on his own eye or that of a key trusted adviser in the organization, he believed that the career season Cabrera had in 2011 for the Royals, his third organization, was the start of something special, not an aberration that would stand up as his career year.

The Giants brain trust read the situation perfectly, and Cabrera reached the All-Star break hitting .353, second in the National League.

Royals general manager Dayton Moore, forever seeking ways to improve the depth of the organization’s pitching, received veteran left-hander Jonathan Sanchez and Triple-A right-hander Ryan Verdugo in the deal. Sanchez didn’t make the American League All-Star team. He fell about eight or nine wins short. With pitching stats that could only be described as dirty, Sanchez has gone 1-5 with a 6.75 ERA in 11 starts, has walked more batters than he has struck out.

Moore viewed Cabrera expendable because Moore thought Lorenzo Cain was ready to take over in center field. After starting the season 2-for-15 at the plate, Cain was injured in the fifth game of the season while making a catch in center field. He has been on the disabled list since then, recovering from a strained left groin and a torn hip flexor. Back from a minor-league injury rehabilitation assignment, Cain will play center for the Royals when the season resumes.

Maybe it’s not entirely fair to call out Moore for misjudging Cabrera’s potential. Maybe Moore is under business-as-usual instructions from ownership. You know the drill: Trade any good player who has one year remaining on his contract while you can get something for him because no way the Royals will pay major-league money to major-league stars.

Cabrera’s a free agent after this season and will command big bucks. With better vision and a more courageous spending approach, the Royals could have locked him up long-term last winter. It’s better to have too many outfielders than one too few. With Cabrera, center field would be the most productive spot in the lineup, not the least.

Hope — fueled by the signing of Alex Gordon to a four-year, $37.5 million extension in March, a year after Billy Butler was locked up for four years for $30 million — burns deeply among those who care about the Royals that things will be different when the time arrives to pay Mike Moustakas, Eric Hosmer, Salvador Perez, Wil Myers, etc.

But is that hope justified? Will the Royals really lock up all of them? Not some of them, all of them.

Even with the Gordon and Butler signings making it seem as if the culture has changed, the reality is the Royals rank 27th among 30 clubs with a $61,391,300 payroll.

Another painful reality: Without the Cabrera trade, the Royals would have a much better offense and a better rotation because any number of starters at Omaha could have produced better numbers than Sanchez. The Royals could be flirting with a .500 season, and the future would look so bright. Of course, it’s within the Royals’ grasp to undo the mistake by signing Cabrera to a long-term contract if he reaches free agency and turning Jeff Francoeur into a fourth outfielder, even though he’s paid like a starter.