Bryce Harper (Getty Images)

It’s easy to dismiss re-signing the Nationals’ Bryce Harper to a $300 million-plus contract extension. He is batting 100 points less than last season’s .319, and despite his 19 home runs he is mired in a career-worst slump.

Meanwhile, Juan Soto has succeeded Harper as a brilliant 19-year-old outfielder who costs pennies versus the latter’s dollars. The team is stacked with outfielders, so maybe the insane money needed to keep Harper beyond this season would be better spent elsewhere.

Then again, Washington’s baseball history says don’t be hasty. Former Senators sluggers Harmon Killebrew and Frank Howard show why the Nats should keep Harper.

Killebrew and Howard both played in seven seasons in Washington, as has Harper. Like Harper, Killebrew spent his first seven MLB seasons in the nation’s capital; Howard’s tenure came during his prime.

And re-signing Harper is all about betting his prime will be as good as Killebrew’s and Howard’s.

Killebrew mostly struggled in his early years, batting only .251 with 84 homers in 390 games versus Harper’s .279 with 169 home runs in 845 games.

Harmon Killebrew puts a charge into one circa 1958 at Griffith Stadium in Washington, D.C. (Photo reproduction by Transcendental Graphics/Getty Images)

But after five sparse years, Killebrew played regularly in 1959 to lead the American League in home runs (42) while earning his first All-Star appearance.

It was the breakthrough long awaited, and “Hammerin’ Harmon” would lead the AL in homers five more times and make another 10 All-Star Games after he and the franchise moved to Minnesota. The first baseman even won the MVP award in 1969 and finished with 573 home runs.

Killebrew was named to the Hall of Fame in 1984. If the Senators hadn’t waited for the 17-year-old to mature, they would have missed on one of the greats.

And that’s the Nats’ greatest fear in letting Harper walk to the New York Yankees or another marquee team; their thriftiness could haunt them for a decade or more.

Howard certainly showed the impact of a big bopper. He was the biggest attraction in Washington from 1965 through ’71 after arriving in a seven-player trade with the Los Angeles Dodgers.

First Baseman Frank Howard #9 of the Washington Senators prepares to swing in the 1960’s at RFK Stadium in Washington, D.C. Howard played for the Senators from 1965-71. (Focus on Sport/Getty Images)

He hit 237 homers in 1,077 games with the Senators with four All-Star appearances. There’s still a white seat in the far reaches of RFK Stadium’s upper deck that blocked Howard’s attempt to hit a ball into outer space.

The Dodgers valued a third starter in getting Washington’s Claude Osteen for Howard, and the reliable pitcher helped Los Angeles win two World Series. But the Dodgers weren’t patient enough to get the best out of their 6-foot-7 first baseman.

Now the Nationals have to decide whether to invest further in Harper to see if he is the legendary player they expected when they drafted him first overall in 2010.

Killebrew and Howard show it’s best to keep Harper at whatever price.

Rick Snider has covered sports in Washington since 1978. Follow him on Twitter @Snide_Remarks