Just demote the whole damn team to Las Vegas. Ike Davis or no Ike Davis, the Mets are a sorry sight and fading fast. But at least they’re finished losing to the Marlins. Last night it was the NL Central-leading Cardinals putting the hurt on this miserable bunch, scoring seven unearned runs in a 9-2 demolition of the Mets at Citi Field. In their first game since Davis was optioned to Triple-A Las Vegas — along with Mike Baxter and Robert Carson — the Mets continued their offensive ineptitude and added shoddy defense to the mix. Daniel Murphy, replacing Davis at first base, committed a throwing error that helped the Cardinals score five unearned runs in the fifth. Two innings later, Kirk Nieuwenhuis misplayed a ball in right field for an error that led to two additional unearned runs. “I don’t how many times we’ve talked about pitching and defense, they go hand in hand,” manager Terry Collins said after the Mets lost their third straight and seventh in eight games. “There’s going to be a lot of talk about, ‘Why Dan Murphy at first base?’ Hey, look, Dan Murphy is a very good first baseman. He didn’t make the play. It just happens.” Jeremy Hefner, in a battle with Dillon Gee for the final spot in the rotation as the Mets await Zack Wheeler’s arrival next week, allowed six runs over six innings, but five of them were unearned. The Mets (23-36) haven’t been 13 games below .500 this early in a season since 1993, when they finished with 103 losses.