The battles to watch in Oilers-Flames as Calgary tries to save its season

The Edmonton Oilers won 5-3 in Game 4 on Tuesday to push the Calgary Flames to the brink of elimination. Expect these four battles to decide if the Oilers advance or the Flames manage to prolong their season.

The headliners

If crowding Connor McDavid were all it took to stop his attacks, he wouldn't have already recorded 10 multi-point games this postseason. Slowing McDavid is easier typed than done. But if an opponent wants to achieve this, they have to be prudent, get back in transition, and get in his way.

McDavid's shiftiness and Leon Draisaitl's niftiness burned the Flames in Game 3 when the Oilers stars had space to race up ice with the puck and reward Evander Kane's straight-line drives to the net. Calgary stuck tighter to McDavid in Game 4, stifling one of his rushes via Erik Gudbranson's knockdown. But the shift continued, and the scrambled defense overplayed Draisaitl, who fed Kane for a goal that typified Calgary's defensive dilemma.

Edmonton's five best forwards have taken over the Battle of Alberta. Kane, Draisaitl, McDavid, Zach Hyman, and Ryan Nugent-Hopkins have scored 16 of the Oilers' 20 goals. All of them except Kane play more than 21 minutes per night. It hasn't mattered that the power play's scuffling at 3-for-19 (15.8%) or that Draisaitl has a banged-up ankle: thanks to his visionary playmaking, he has 13 points in four games to McDavid's 11.

Two lines are powering the Oilers, and shadowing them has to be a 60-minute endeavor. The Flames scored nine times in Game 1 but didn't coast to victory because they blew a four-goal lead. They lost a two-goal cushion midway through Game 2 and faltered late. Tuesday's 3-0 deficit proved too steep to overcome.

Calgary's top line was the best in the league at five-on-five this campaign but hasn't scored in that situation since Game 1. Johnny Gaudreau's declining output exemplifies the problem. He scored 3.58 points per 60 minutes in the regular season, 2.83 against the Dallas Stars in Round 1, and 2.27 so far versus Edmonton. McDavid and Draisaitl have been superb, and Gaudreau and Matthew Tkachuk are running out of time to measure up.

The defensive efforts

The harsh truth of the playoffs is that the team that makes the most mistakes - or screws up once too often when the score's close - tends to lose.

Defensive malfunctions bedeviled the Oilers throughout Game 1 and early in Game 2, but they've cleaned that up and have now been sound for most of the series. They minimized errors during the Edmonton homestand, unlike Calgary. Jacob Markstrom's misplay gifted Nugent-Hopkins the first goal in Game 4. Oliver Kylington got caught standing flat-footed behind Nugent-Hopkins as he banged in the decisive rebound.

The Flames' irresponsibility enabled Kane to pot his Game 3 hat trick. In a six-minute span, Blake Coleman made an errant drop pass; the Gaudreau line didn't backcheck with gusto after an offensive shift; and Rasmus Andersson pinched to hit Draisaitl as he head-manned the puck, which gave Kane a head start in a footrace with Brett Ritchie. Kane sprinted to the crease and scored on each of those breakouts.

On the plus side, Chris Tanev stabilized Calgary's defense during his shifts Tuesday. The Flames didn't allow a goal or high-danger chance over his 17:12 of ice time at five-on-five, per Natural Stat Trick. Calgary outscored Edmonton when Tanev defended McDavid at five-on-five this season, so his return from injury supplies hope that he could tilt the ice in tough minutes in Game 5.

The goalies

Edmonton's home games showcased both sides of Mike Smith's netminding - the good and ugly.

Smith was at his most effective in Game 3 for reasons beyond his 32 saves. His timely stops and inclination to make plays directly led to two Edmonton breakouts and goals, including when he caught Mikael Backlund's shorthanded wrister and slid the puck to Draisaitl instead of covering it. Draisaitl set up Hyman to score on the ensuing rush.

Smith's proactive mindset was hazardous in Round 1. The Los Angeles Kings picked off one of his outlet passes to net a game-winner. Against Calgary, though, Smith sprung Draisaitl for a breakaway goal and looked formidable for long stretches of play. Then he let in two goals in 36 seconds in Game 4 and got fooled by Andersson's 132-foot slapper, resembling an outfielder who lost the ball in the lights.

Markstrom tied Smith with one blunder Tuesday, and he also missed a tipped shot and two rebounds. His save percentage for the series is .850, much worse than his .943 mark against Dallas and the .922 figure that landed him a Vezina Trophy nomination. To beat the Oilers three straight times, he'll probably have to steal a game and surely can't afford any more stinkers.

The secondary scorers

By tallying twice Tuesday, Nugent-Hopkins snapped his seven-game goal drought in style. He and his linemates, Hyman and Kailer Yamamoto, executed a textbook dump-and-chase and won a puck battle to key the late game-winner. The shift summed up why complementary scoring is a classic playoff X-factor.

That said, Edmonton's barely gotten - or needed - offense from guys outside of McDavid and Draisaitl's orbit. Nine Edmonton skaters have zero points this series, including every forward on the third or fourth lines. That gulf obviously hasn't been an issue, though that could change in future rounds should the Oilers finish the job at hand.

On the Calgary side, Dillon Dube has been held to one assist and fanned on a promising one-timer Tuesday after netting 18 goals this season. Calle Jarnkrok's 31-game goalless skid began before his trade from the Seattle Kraken. Backlund scoring in Game 4 wasn't enough. The top line and secondary sources need to produce in tandem for the Flames to extend the series.

Nick Faris is a features writer at theScore.