Well, I've done a lot of fighting and I know that to kick from the ground upwards towards the crotch is a very useless manoeuver.
You're likely to get no further than the knees.
It's better to lift your leg and kick outwards towards the groin but this is still not guaranteed to work.
The best time is when they are dodging a punch backwards as they are using their legs to counter balance and it's not as easy to bring their knees together.
If you miss though, you leave yourself wide open. If they catch your leg, you're fucked.
Ball kicking is really only effective if the guy's not paying attention.
You're likely to get no further than the knees.
It's better to lift your leg and kick outwards towards the groin but this is still not guaranteed to work.
The best time is when they are dodging a punch backwards as they are using their legs to counter balance and it's not as easy to bring their knees together.
If you miss though, you leave yourself wide open. If they catch your leg, you're fucked.
Ball kicking is really only effective if the guy's not paying attention.