WEST SACRAMENTO, Calif. – If the Cincinnati Reds come up short in their long-shot bid for a playoff berth down the stretch, their three-and-out against the Athletics over the weekend will serve not only as a major part of the elimination math but also as a booming reminder of why.

Booming as in boom.

The Athletics hit four more home runs to come from behind to beat the Reds 7-4 on Sept. 14 at minor-league Sutter Health Park along the Sacramento River to sweep a series in which they out-homered the punchless Reds 10-4.

“We just couldn’t keep it in the ballpark,” manager Terry Francona said, singling out A’s rookie Nick Kurtz, who hit an opposite-field shot for the lead in the fifth off Reds starter Nick Lodolo one night after hitting the longest home run in the majors this season over the batter’s eye.

“That kid, their 3 hole hitter, he hits the ball to left field like that, that’s good hitting.”

Maybe by this time next year, the Reds will have their own 30-homer slugger in the middle of their lineup putting them in stronger position for October than this year’s fast-fading position.

It’s been a theme all season, but especially of late for the stutter-stepping Reds, who rank among the bottom eight teams in the majors in home runs despite playing in one of the most power-friendly ballparks in the majors.

The A’s have five players who have hit more home runs than the Reds’ home run leader, Elly De La Cruz, who hasn’t hit one since July 31 and only the one since June 23.

The A’s hit three or more in each of the three games against the Reds, whose lineup has 19 such games of its own all season – and only that many because of Sal Stewart’s solo shot to the roof of the clubhouse on the other side of the left-center wall in Sunday’s eighth after the Reds trailed by four.

Making matters sting a little deeper as they headed out of Sacramento on a long flight to St. Louis for their next road series was the fact that the New York Mets picked Sept. 14 to end an eight-game losing streak – boosting their lead over the Reds for the final wild-card spot in the National League to 2 1/2 games.

Worse yet for the Reds was the fact that those objects in the mirror last week indeed turned out to be larger than they appeared.

The Diamondbacks won for the third time in four games Sunday to move a half-game in front of the Reds – putting the Reds behind three teams for the final playoff spot with four series left in the season.

After the Giants lost to the Dodgers on Sunday, here’s what the battle for the final NL wild-card spot looks like heading into the week (games remaining in parentheses):

Mets (12) — 77-73  —Giants (13) — 75-74  1 1/2 GBDBacks (12) — 75-75  2 GBReds (13) — 74-75  2 1/2 GB

It’s only the second day since June 9 the Reds have been under .500 (also Sept. 5).

They become the second visiting team in major-league history to ever get swept in West Sacramento, California, joining the Detroit Tigers and now have lost 39 games this season in which they held the lead (tied for fifth-most in MLB).