Yes and no. Unless the players are coming in for breakfast lunch and dinner, there's only so much control you can and should have over a players choice of diet.
On one extreme, we have professional cyclists that are able to measure and monitor to a gram their intake. Most cyclists are only in touch with their teams for short periods during racing. Outside of that, an individual is taught how and what they should be eating.
Education is a big part of sport and we've seen even at schoolboy level it happening.
I would be careful using cyclists as the prime example for what sport's people put in their bodies.
I think the above image showing Len beating 17 players pretty much highlights the Wallabies current issues.
We don't have major issues when we are attacking.
Yes, our forwards could bend the line a bit more and we are occasionally a bit sloppy ball in hand but our attack is OK.
Our defense is appalling, and it is not the individual one on one defense it the structure we have in place and application of the defensive gameplan.
You cannot run a passive defense unless you have complete confidence that you are not going to miss any tackles or make misreads.
An aggressive in your face rush defense is far more forgiving on the defensive errors as you often have the opposition attack on the backfoot so it is harder to pounce on mistakes.
We actually seem to be running a hybrid defense where the FB and wings are given license to rush out of line but everyone else holds a passive position.
Maybe I am missing something but I just cannot see how this can work.