I wouldn't say Ronda has no chance.
She has the equivalent of James Toney's punchers chance in his MMA fight V Randy. It is just flipped around.
Ronda has basically one Damian Maia/Anderson dive attempt to try and trip up and get the fight on the ground otherwise she will be in for a world of hurt.
Floyd has every thing else going for him over her if she cannot pretty much instantly secure it.
What Ronda cannot do is hesitate at the opening bell. She should literarily scream and just run at Floyd like a Banshee and hope he spends more time trying to avoid her then to counter her, and they then somehow end up in a heap on the ground.
If she does hesitate, if she does try to set up her td or out reflex and athleticism Mayweather to close distance from a flat footed stop it will look worse for her then the below gif which is showing the incredible speed difference between two elite boxers, one of which is arguably up their with Floyd in terms of speed and counter punching prowess and the other who is elite but not in those areas, in RJJ v Toney.
Just imagine Ronda, standing at the bell across from prime RJJ or Mayweather, in a gun slinger like duel in terms of who can move first, strike fastest and make it count.
Ronda is thinking 'I need to shoot, I need to get this guy down', meanwhile RJJ or Floyd have already moved and landed that type of punch on her jaw.