The microcosm of the good and bad Edmonton Oilers’ free-wheeling loss Sunday to the Chicago Blackhawks was defenceman Philip Larsen, who had three assists but still finished minus-three. “Three points, but I was on for four of their goals,” said Larsen. With Justin Schultz having missed the last five games with a sore groin, Larsen slid into his spot on the first power-play unit. He set up power-play goals by Nail Yakupov and David Perron and also helped on Ryan Nugent-Hopkins’ score, but two Blackhawks forwards — Andrew Shaw and Marcus Kruger — got in behind him for all-alone goals on Devan Dubnyk. He wasn’t close enough, either, to big Bryan Bickell, who had an easy tap-in outside the goalcrease. As Larsen, who came to the Oilers in the Shawn Horcoff trade, prepares to play his old Dallas Stars’ team on Wednesday at Rexall Place, it’s hard to figure out where he fits in. Can he stay in the top-six defencemen when Schultz returns, or will he be back in Oklahoma City, making his $1.1 million in the American Hockey League? He can skate, shoot and distribute the puck, but can he defend? But he’s not the only one like that on the Oilers, who have been horrendous defensively — 52 goals against five-on-five and only 30 for. They’ve given up a staggering 75 goals over 19 games, 47 more than the Colorado Avalanche. Whatever defensive system coach Dallas Eakins is employing, it ain’t working. Veterans are making errors that teenagers make; the offensive young guns don’t have enough defensive savvy. They don’t work legal picks nearly enough to allow their defencemen an extra second to move the puck, they allow teams to dump pucks behind their net and, rather than cut them off, they passively stand by. Talking about Larsen specifically, he’s been better than a lot of Oilers, even if he’s minus-five in his five games. But he’s a poster boy for what’s right and what’s wrong. Eakins gave Larsen a fair shot in training camp, but the Oilers kept Anton Belov over him, opting for size. Now they’re playing together. Larsen has played more than 20 minutes four straight games. “I wasn’t sure what he would be because I didn’t know who he was. I wasn’t keeping tabs on the Dallas Stars last season,” said Eakins. “I thought he was good in training camp, but coming back, he’s played well.”