In order of importance
1. Genetics
2. Training stimulus
3. Diet
4. Legal supplements
Illegal supplements can be so effective, you'd probably put them in front of genetics.
Aussie Rules is a sport where creatine would have one of the best potentials for benefit. Water retention is not really a major side effect when used in controlled dosage. In the original trials they only used around 5g a day after the initial loading phase. This dosage won't, in my experience, cause much water retention, particularly if it's high quality micronised creatine.
There's evidence to suggest caffeine counteracts creatine's benefits. It's possible they'll use creatine in the off-season/pre-season and caffeine during the season.
Everyone's different though and creatine doesn't benefit a lot of people so this is not a golden rule. Different players will use it differently.
creatine does have some benefit for sure
but the old crushed coffee, aspirin and sudafed used to work wonders before the gym. tasted terrible tho





