In the post-mortem of their heavy 4-0 loss to Sydney FC, it is clear that a few crucial things went wrong for the Western Sydney Wanderers in their opening round clash.

Here are five flaws that stood out on the night:

1. Too many new faces in the squad

While they may have had a taste of the action in pre-season, nothing can truly prepare a player for their A-League debut with a new club. Playing with a fresh bunch of teammates in an unfamiliar set-up, new squad members need time to find their feet as Tony Popovic admitted post-match. It was therefore a little surprising to see five new Wanderers make their first appearance for the team in such a huge opening game. Though they can’t be blamed for the loss, with Jumpei Kusukami in particular impressing, their inclusion certainly made things difficult from the outset.

2. Hamill caught out at left-back

A natural centre-back, Brendan Hamill was played out of position in the derby and you could certainly tell he wasn’t comfortable. Filling in at left-back with Scott Jamieson leaving in the off-season, Hamill struggled to track his man and if he wasn’t directly at fault for the first, he certainly could be blamed for the second and fourth goals.

Winning just six of his twelve duels, committing two fouls and being dispossessed twice, it really wasn’t Hamill’s night. With Jack Clisby recruited in the off-season, who himself may not be as good as Jamieson, for the time being he is more suited to starting at left-back than Hamill.

I presume people are on to this already but boy oh boy, Brendan Hamill sure ain't a left back.

— Andrew (@andrew_54) October 8, 2016

3. Lack of cutting edge up front

With yet another clean out at the club during the off-season, the Wanderers frontline lost the reliable albeit ageing Mark Bridge with young gun Kerem Bult his replacement. Despite looking lively in the derby it’s clear Bulut will fill a very different role to Bridge and may struggle to hit the target quite as often, as showcased on Saturday night. Popovic was also happy to keep just the one striker up front all night for the derby with Brendon Santalab replacing Bulut with fifteen minutes to go despite being two goals down. Perhaps Popovic needs to reassess this formation with the Wanderers desperately lacking a cutting edge on Saturday night.

4. Second-half slumber

After a tight tussle in the first half, the Wanderers may have physically returned from the break but mentally they were elsewhere. Giving away what Popovic rightly called two very soft goals in the opening ten minutes, the Wanderers never really returned after the break and were made to pay by a switched on Sky Blues side.

5. Little brother complex?

Having now failed to win eight derbies in a row, it’s clear the Wanderers are struggling against their elder Sydney brother. With less big game experience and possible self-doubt now creeping in, it would seem the Wanderers are succumbing to a bit of a little brother complex where they’re lacking the belief they can take their bigger brother down.