If there's anything to be learned from recent domestic violence incidents involving NFL players Ray Rice and Greg Hardy aside from the fact that photographic evidence seems to make all the difference when it comes to outrage, it's that there still are blurry lines when it comes to women who are violent against men.

Take Ronda Rousey, for instance. The UFC fighter/budding movie star joked about Floyd Mayweather's past when she said, "I wonder how Floyd feels to be beat by a woman for once" after besting him for an ESPY award last summer.

But Rousey, in her autobiography, described a harrowing incident in which she repeatedly struck her ex-boyfriend, MMA fighter Timothy DiGorrio, after discovering that he had taken nude photos of her. In My Fight, Your Fight, she describes confronting the man she called "Snappers McCreepy" and slapping him so hard "my hand hurt."

GETTY IMAGES The undefeated Rousey is preparing for Saturday's fight in Melbourne against fellow American Holly Holm.

"I punched him in the face with a straight right, then a left hook," she writes. "He staggered back and fell against the door."

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"[Expletive] my hands, I thought. I can't hurt them before a fight."

"I slapped him with my right hand. He still wouldn't move. Then I grabbed him by the neck of his hoodie, kneed him in the face and tossed him aside on the kitchen floor."

The fight ended when she walked out to her car and he jumped into the passenger seat, asking her to hear him out. "I walked around the car, pulled him by the neck of the hoodie again, dragged him onto the sidewalk and left him writhing there as I sped away."

Rousey, who is preparing for Saturday's fight in Melbourne against Holly Holm, did not respond to a request from Yahoo's Eric Adelson or The Washington Post for comment.

As Adelson points out, this is a murky area. He noted that the US Justice Department defines domestic violence as "a pattern of abusive behaviour that is used by one partner to gain or maintain power and control over another intimate partner."

It is unclear whether there was a pattern and DiGorrio, like many men, did not call police.

Still, "I'm not comfortable with her behaviour," Kim Pentico of the National Network to End Domestic Violence told Adelson. "What I am absolutely not willing to say is she's committed domestic violence without speaking with him and learning more about that relationship."

Rousey isn't the first high-profile female athlete who found herself on the other side of abuse.

Hope Solo, the goalkeeper who helped lead the US women's soccer team to World Cup victory last summer, continued to play for the team while a court case in which two relatives accused her of striking them in a family incident wound its way through the courts.

Initially dismissed, the misdemeanour case is back on after a prosecutorial appeal. A new date has not yet been set.

There were plenty of questions and disbelief when Solo continued to play for the US team. USA Today's Mike Foss bluntly called Solo the "train wreck" the Americans were riding to a title.

The New York Times' Juliet Macur wrote in a column titled "Hope Solo Is a Hero on the Field. Repeat, on the Field." and has written of the disparity between how men and women are treated:

"Instead of sending a quick and powerful message soon after her arrest by punishing Solo in some way, US Soccer now has a woman in goal who is accused of saying and doing some very ugly things - not exactly the kind of poster woman you'd want for a team."

"But this woman sure can leap and dive and scramble for the ball and keep it out of the goal, where she is the best Hope Solo she can be. She's the phenomenal athlete between the goal posts, what I've called the loneliest place in sports."

But the US team won it all and Solo went to the White House with her teammates.

There are, of course, no photos of the incident Rousey describes and those appear to offer a tipping point, as video of Ray Rice knocking out his then fiancee in February 2014 and police photos of Nicole Holder, who was struck repeatedly by Hardy of the Dallas Cowboys, show.

There was outrage over the Hardy pictures, but Rousey's incident was barely a blip. ​

Outside of photographic proof, men are reluctant to come forward, partly because there often is less harm, but that only enhances the notion of a double standard.

Maybe the best standard of all is just for everyone to stop with the hitting.