You can’t see me now, but I’m jumping up and down and waving my arms like a cartoon guy marooned on a desert island trying to flag down a distant steamship.

The steamship in this case is Farhan Zaidi and Larry Baer of the Giants, who are trying to sign Bryce Harper, which would be a colossal mistake.

Maybe I’m too late. Baer and Zaidi were in Las Vegas on Tuesday — again — trying to close the deal with Harper.

The Giants seem to be desperately trying to catch a nice fish, but if they are successful, they will take themselves out of the running for the biggest fish: Mike Trout.

The Giants should tell Harper to go spit in his hat. Not that Harper will be overpaid when he signs with some team at around $30 million per year for a decade, because he deserves whatever he gets. But for the Giants, it is the wrong way to go.

Trout will be a free agent two years from now, unless he re-ups with the Angels, which seems unlikely.

If the Giants sign Harper, they almost assuredly will not be a player in the Trout sweepstakes. That would be tragic.

Trout is the best player in baseball. Sports Illustrated ranks him No. 1, easily. MLB.com ranks him No. 1. Harper? MLB.com ranks him No. 15, Sports Illustrated has him at No. 20.

The Giants are rebuilding. They have no choice, with so many older and untradeable players. They won’t be a strong contender this season, even if they land Harper. And probably not next season. But in 2021, when Trout will be available? The Giants will have a lot of money coming off the books, they will have some rising potential stars, and they can overpay for Trout and build their young team around the game’s best ballplayer.

The Giants have a commitment to their fans. And to their investors, in the form of ticket sales. It would be hard for Baer to tell fans and shareholders, “Be patient for a year or two while we rebuild.”

But that’s what the Giants should do. Harper would be a short-term semi-solution who might bring more fans to the yard this season, but would almost guarantee the Giants would miss an opportunity in 2021 to grab their future.

Trout — have you seen him play? Forget baseball, he might be the baddest man in sports. He is LeBron James in spikes. He doesn’t play the game, he attacks it like a lion attacks a limping zebra.

Harper is a fine player, but Trout is a better defender, baserunner, hitter and teammate, and is more durable.

Trout has a career .307 batting average and a .990 on-base plus slugging percentage. Harper is .279 and .900. Harper won the MVP in 2015. Trout has won two MVPs and was runner-up four times.

Trout, 27, is one year older than Harper, but Trout is just getting warmed up. Last season was his best in several significant categories.

Manny Machado signed with the Padres, Nolan Arenado re-signed with the Rockies. If Harper goes to the Phillies, the case could be made that these three opted to go with lower-profile teams, avoiding the massive pressure that comes with joining a bright-lights team like the Yankees or Dodgers.

The guess here is that Trout would relish the opportunity to be the savior, the man expected to lead a great team in a spotlight market back to the top of baseball.

The Giants are a big-market, big-ambition team, and they need their next Buster Posey.

Forget pitching for a moment; Posey was the key man in 2010, ’12 and ’14. From the moment he buttoned up the Giants’ jersey, Posey not only accepted the leadership position, he embraced it.

That’s what the Giants will need going into their next incarnation.

Trout and his agent, Craig Landis, were criticized for signing a relatively short-term (six seasons) contract with the Angels, through 2020. Landis (whose father was Jim Landis, an outfielder for the White Sox in the ’50s and ’60s and a graduate of Richmond High) explained at the time, “What Mike was trying to accomplish was some financial security, but also keeping the door open for whatever may happen down the road.” (Italics mine.)

What may happen two years down the road is an opportunity for Trout to join the Giants.

Or the Giants could sign Harper now. Their fans still will get to see a lot of Trout in two years, every time the Dodgers stop by.

By the numbers How outfielders Bryce Harper, 26, and Mike Trout, 27, compare: Harper 2018 Trout 2018 Harper career Trout career Games 159 140 927 1,065 Avg. .249 .312 .279 .307 HR 34 39 184 240 RBI 100 79 521 648 SB 13 24 75 189 OPS .889 1.088 .900 .990

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Scott Ostler is a San Francisco Chronicle columnist. Email: sostler@sfchronicle.com Twitter: @scottostler