It's arguably the toughest job in the A-League. So what does the Sky Blues' would-be saviour have to focus on if he is to bring back the glory days?
By Iain Strachan
1. Develop an on-field identity
As a team, the Sky Blues have rarely stood for anything meaningful. In the beginning they were the league's glamour club, propelled to the title by former Manchester United star Dwight Yorke. Since then, who knows?
Brisbane Roar and Melbourne Victory like to keep the ball, a legacy of Ange Postecoglou's time in charge at both clubs. Adelaide United are everyone's favourite Catalan outpost in South Australia.
Western Sydney keep it tight, make it difficult for opponents to play and exploit any weaknesses they can find. The Mariners were similar under Arnold, the overachieving underdogs making the most of their meagre resources.
A choice now has to be made about which direction the Sky Blues go in. Will the players at his disposal dictate Arnold's strategy and tactics at Sydney FC? Or will he go out and sign talent to suit a new specific system?
2. To marquee or not to marquee?
Reports on Wednesday indicated the Sky Blues hierarchy would provide their new coach with substantial funds to go out and sign a new marquee player. That wasn't Arnie's style at the Mariners, owing to financial constraints more than anything else.
Does the size and prestige of Sydney demand they recruit a top-line star? Or can Arnold create a team capable of selling tickets through their results and by playing entertaining football?
3. Win back the fans
An issue intrinsically linked with the first two points. Numbers aren't necessarily the problem. Sydney had the second-highest average crowds in the league last season, behind only Melbourne Victory. There will of course be concerns that those figures could fall without Alessandro Del Piero. But repairing the relationship between supporters and the club hierarchy is more of a priority.
Frank Farina was distinctly unpopular with some supporters last season, particular the active fans in The Cove, but the club's senior administrators were not spared that displeasure either. If Arnold is to appease the angry masses, it will be through saying the right things in the media and getting results on the field. Attendance will the take care of itself.
4. Unite the dressing room
There was an ugly flare-up of tensions in the Sky Blues' squad last year, with Nick Carle and Matt Thompson briefly banished from first-team training before PFA pressure saw them reinstated. But creating a genuinely unified dressing room will be about more far than appeasing senior professionals or averting training ground fisticuffs.
Arnold needs to try and recreate the strong team spirit and bond between his players in Gosford, a unity which equipped the Mariners to survive his departure and the loss of numerous key players in the last 12 months and still remain competitive.
5. Leave a legacy
So many coaches have come and gone at Sydney without having a long-term impact or leaving something meaningful for their successor to build on. The same certainly can't be said of Arnold's time at Central Coast, where shrewd recruitment and a focus on youth development has set the club up to prosper under Phil Moss.
It won't be easy to do the same in the Harbour City, where expectations are bigger and scrutiny far more intense. Perhaps more than simply improving results and competing for silverware, the biggest challenge for Arnold is to drive a generational change in the culture of the club. It will be a task the 50-year-old is relishing and certainly capable of. Will he be allowed the time and given the scope to do so?