THEY say good things come in threes. But what about bad things?

It's a question Sydney will be asking, after three 50m penalties set the tone for a regrettable Saturday afternoon defeat to Essendon that has Dean Cox's first season in charge of the club hanging by a thread.

BOMBERS v SWANS Full match coverage and stats

If ever an opening quarter could sum up a season, here it was. The Swans first overstepped the mark to hand Nate Caddy the game's opener, then sent Caddy to the goal line by knocking the ball from his hands moments later, before failing to adequately stand the mark again to put Saad El-Hawli within striking distance.

Just like that, Essendon's platform for victory was laid for it. Sydney, already with plenty of reason to feel sorry for itself this season – its injury list speaks to that – this time becoming the architects of its own downfall in a shoddy 11.5 (71) to 8.15 (63) loss that will haunt Cox and his depleted side.

Sydney's nightmare barely ended there. It gave away yet another 50m penalty just minutes into the second term, the fourth of six for the match, before conceding six of the next seven goals as Essendon rampantly ripped into its downtrodden foes. It would be this passage the Swans would regret amid a brave comeback later on.

Nic Martin (38 disposals, five tackles), Andrew McGrath (35 disposals, 11 marks) and Mason Redman (32 disposals, one goal) played the grateful recipients of Sydney's series of gifts, guiding the club to its biggest scalp of the season yet.

But to say this was all Sydney's undoing would be unfair on Essendon and the moments of brilliance weaved in amid the litany of opposition errors. Zach Merrett, tied up by James Jordon for much of the game, provided the majority of them through the second quarter run that stretched the margin to 39 points by the main break.

Going forward to break the hard tag, Merrett first marked strongly and snapped truly to kickstart his afternoon. He then darted out of traffic moments later, producing a trademark running finish on his left to ensure the Swans' Jordon-plan went up in smoke within an instant.

In among a classy first goal from debutant Archer Day-Wicks, a rousing snap from Sam Durham and an exciting chase down tackle from Isaac Kako that led to another, the Bombers had done more than enough themselves to engineer a fifth victory from their last six games.

It was the type of ruthlessness Sydney lacked at the other end. Nick Blakey had five intercept marks to quarter time – the AFL record is 10 in a match – giving an indication of the side's initial ability to stop Essendon. But, at the other end, the Swans could only produce two scores from 16 inside-50s to quarter-time, and two goals from 26 entries to half-time.

Sydney looked sharper to begin the second half. It had 17 entries to nine in the third quarter, and nine scoring shots to five, but yet the same problems persisted. At one end, Aaron Francis somehow screwed a snapshot wide from the goal line. At the other, a sublime passage from Martin set up Caddy's third from the same position.

But the Swans had still shown a glimpse of what they were capable of. That glimpse turned into total Bomber tension when substitute Angus Sheldrick's goal was quickly followed by another from Justin McInerney to start the final term, reducing the deficit to just 15 points with 10 minutes to play.

Will Hayward would add another, bringing the margin to single digits, but time was against the battling Swans.

How the visitors would rue their missed opportunities in the second half. Even more, though, how they would rue the three 50m penalties that created that deficit in the first place.

Contrasting fortunes for baby Bombers
There was heartbreak for Essendon's fourth AFL debutant of the year, with Lewis Hayes leaving the ground late in the third quarter with what appeared to be a serious knee injury. The key defender, who had replaced a hamstrung Jordan Ridley in the Bombers' backline, had performed admirably to that point, only for his night to end in concern among the club's bench. The side's fifth debutant, Archer Day-Wicks, was another nice contributor and kicked the first goal of his career with a clever gather and snap during Essendon's terrific second quarter run. The pair added to Isaac Kako, Tom Edwards and Saad El-Hawli, who had already won their first guernseys earlier this season, in an exciting Bombers side that's seemingly getting younger by the week.

Bad kicking is bad Swans footy
For as much as the early 50m penalties gave Sydney coach Dean Cox reason to be kicking himself, the side's inability to convert the chances it eventually created at the other end would have been just as frustrating. The Swans booted 11 behinds from 17 scoring shots in the second half, with a number of senior and experienced players missing both set-shots and wide open opportunities on the run. Aaron Francis' wayward effort from the goal line was the worst of them, but the former Essendon man was hardly the only culprit. It ensured for another brutal Swans afternoon, with Cox's team now 3-6 and facing an uphill battle to return to September later this season.

Bombers skipper marvels at Marvel
Sometimes you just have to marvel at Zach Merrett. Copping a hard tag from 100-gamer James Jordon, the Essendon captain was held to just two disposals throughout a frustrating opening quarter. The response? Change the game from a different role. After going forward to start the second term, Merrett marked strongly on the lead to kick his first before weaving out of traffic and producing another stunning running finish moments later. Within an instant, Merrett had helped kickstart a run where the Bombers slotted six of the next seven goals to take the game away from the Swans.

ESSENDON    3.1    9.1    11.4   11.5 (71)
SYDNEY        1.1    2.4    5.10    8.15 (63)

GOALS
Essendon: Caddy 3, Merrett 2, El-Hawli, Day-Wicks, Perkins, Kako, Durham, Redman
Sydney: Hayward 2, McLean, Grundy, Campbell, Co.Warner, Sheldrick, McInerney

BEST
Essendon: Martin, McGrath, Reid, Setterfield, Redman, Caddy, Durham
Sydney: Blakey, Grundy, Rowbottom, Ch.Warner, Roberts

INJURIES
Essendon: Hayes (knee)
Sydney: Nil

SUBSTITUTES
Essendon: Dylan Shiel (replaced Lewis Hayes at three-quarter time)
Sydney: Angus Sheldrick (replaced Ben Paton in the third quarter)

Crowd: 43,799 at Marvel Stadium