OPINION: A good rule to stick by when judging any A-League team is to wait until Christmas to assess how good they are.

At that stage, about a third of the season has gone and early form fluctuations should have started to flatten out.

This rule was particularly pertinent for the Wellington Phoenix this year. It would have been easy to write them off again after a three-match losing streak saw them second-bottom after five rounds, given how previous seasons have gone after similar starts.

But coach Mark Rudan made a few changes, brought a few improvements forward and they were able to record their first three-match winning streak since March 2015, allowing them to enjoy their pavlova on Christmas Day firmly ensconced in the top six.

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So what has changed in the short-term to get these on-field results? And what broader changes has Rudan made to get the whole club finally moving in the right direction?

MENTALITY

GETTY IMAGES Louis Fenton gets a piggy-back ride from his Wellington Phoenix team-mate Alex Rufer.

"We've got to change the mentality of this whole football club."

The number of times Mark Rudan has said that since arriving in Wellington in May is astounding.

He challenged all his backroom staff, the management staff, the owners and even the media to change how they think about the club.

When you first heard it, it was hard to think mentality could play that big a part in on-field results.

But the biggest change this season has been the positive, tight-knit mentality of the squad, and the results have followed.

All through last season and early this season, when they went a goal down, it was a sense of "here we go again" as the shoulders slumped and heads dropped.

GETTY IMAGES It was one of the first times the Wellington Phoenix players have celebrated like this in front of their home fans.

But now, they're flying. Of course, they haven't trailed at any time in their four-match unbeaten run, but they have conceded unfortunate equalisers and still picked themselves up to get draws or wins from matches.

The show of unity after their 4-1 win over Brisbane Roar last weekend, in which they all held hands and jumped about in front of their fans, was something few people could recall seeing from a Phoenix team.

If they keep that togetherness up, and individuals keep putting their team ahead of themselves, then they will continue to pose real problems for every team in the league.

TACTICS

HAGEN HOPKINS/GETTY IMAGES The Wellington Phoenix celebrate Roy Krishna's goal against Brisbane Roar last weekend.

It's not all in their heads.

Rudan has fast-tracked what he wanted to his squad to do on the field and they've shown themselves adept at implementing the gameplan.

The 3-5-2 shape hasn't changed since the start of the season, but what was a flat back five has changed to a genuine back three, with wing backs Louis Fenton and Liberato Cacace urged to push further up the field. That forces the opposition wingers to either drop deeper, or risk their midfield and defence being overloaded.

Centre back Steven Taylor and striker Roy Krishna have become the two most important players on the field given one of their main tactics is for Taylor to hit Krishna with long balls in behind the defence. The timing of the ball and Krishna's run needs to be perfect for it to work.

It's little wonder Krishna leads the league in offsides because of it, but even if he doesn't win the ball, the idea is to press the opposition so they win the ball back high up the field.

It's a simple tactic, but, when combined with their impressive full team press, has proved to be an effective way of playing in the right areas of the field.

X-FACTOR

RAGHAVAN VENUGOPAL/PHOTOSPORT Wellington Phoenix midfielder Sarpreet Singh has been lauded as one of the best players in the A-League.

﻿The Phoenix do not have the most talented squad in the league. They can't afford big-money marquees. What they have is a team full of solid journeymen who are playing their roles well, some youthful enthusiasm and a couple of exciting, impactful players.

Krishna's pace will trouble any defence, but it is 19-year-old Sarpreet Singh who has become the shining light, leading former Socceroos goalkeeper and Fox Sports pundit Mark Bosnich to crown him as the best player in the A-League at this moment in time.

Ahead of Japan international Keisuke Honda. Ahead of Sweden international Ola Toivonen. Ahead of Dutch international Siem de Jong.

The kid can play. He ripped Brisbane apart last weekend, after earlier in the season finding himself out of the squad. There were a few reasons for that and not all of them need to be public knowledge, but what is public knowledge is how he has comeback from that and set the league alight. Every successful team needs a player like him and he has timed his breakout season perfectly for Rudan and the club.

Words of caution do ring out as well, given Rudan's project remains a work in progress, with much development still to come.

Only one of their four wins this season has come against top-six opposition.

That makes their next three matches, all away from home, as a big litmus test for how the rest of the season might go.

It starts with second-placed Melbourne Victory on Friday night, then two games in four days against eighth-placed Western Sydney and seventh-placed Adelaide.

Four to six points from those matches and the bandwagon should really start to swell. Fewer than three and it's hardly panic stations, but the doubts might start to creep back in.

AT A GLANCE

What: A-League round 10

Where and when: AAMI Park, Melbourne, Friday 9.50pm

TAB: Melbourne $1.50, Phoenix $5.50, draw $4.25