I love how we all sit here saying get rid of X and replace him with someone better who will deliver results from Day 1. As if it's that easy.
A player delivering in one environment may not necessarily deliver in another. There are expectations off the field as well as on, in terms of fit. There must be a reason Goodwin wasn't picked up by Adelaide at the time. Perhaps he didn't demonstrate consistency, or was carrying minor injuries, or his diet, health or mindset wasn't quite right. Perhaps it was an administrative oversight. Perhaps the roster didn't quite have enough room. Beauchamp was playing at a world cup not that long ago, yet he didn't "cut it" at Heart. Williams was the next big thing in Australian football, now he's a "waste of a contract".
As much as the A-League has improved, it's not exactly a destination of choice for leading talent. There's a salary cap, there's no transfer budget, the clubs are treading a fine line financially, there's no marketing, etc., etc. Roar went 36 unbeaten and have now lost 6 this season. There's a reason why the teams are so close. Injuries do play a huge role because clubs can only afford consistent performers in a small number of positions and then try and make the most of the rest of the cap. Injuries to key players mean there's limited depth. It's only those clubs that have moved to "systems" as opposed to individuals that have been able to achieve success for a period of time, and then only while they have the personnel fit to deliver the system. It's a league of fine margins!
Sometimes you are better off focused on how you can get more out of what you've got than from restarting from scratch with new personnel.