Do you train in karate or some related style? How often do you work ground techniques at your school? Most karate students train on a traditional wooden deck, so if some rolling or grappling moves are required, somebody is recruited to go into the back room to pull out some small cheesy mat to work out on. Some basic takedowns and rolls are shown and then the obligatory mat disappears for another three or four months. At least that's been my experience. Karate is simply not about ground techniques and never has been. Actually, this is surprising given the history of tegumi (Okinawan wrestling) which actually predates karate, yet never influenced karate's development.
In karate, certain techniques taken from kata do resemble jiu-jitsu moves, but you'll find none of that in a sportive karate match. From what I've seen karateka don't like to be grabbed in any way when sparring. Most people - including black belts - don't really respond properly to this maneuver, despite endless repetitions of bunkai or self-defense drills. Sport and reality tend to be mutually exclusive within the karate realm.
Longtime columnist Dave Lowry once suggested that karate techniques can never be practiced realistically. There's a certain amount of truth to this, as strikes, particularly to vital areas, are taught to be pulled without hurting the opponent. In arts such as judo, Lowry explains, a hip throw can be executed full force without splattering the other guy. In this way, the judoka can come to appreciate a realistic sense of close quarter combat that cannot be fully realized by the karate practitioner. This could be one reason grapplers usually prevailed against strikers in the early years of MMA matches. The following is an old clip featuring Royce Gracie of Brazilian jiu-jitsu against some hapless kung fu guy:
A couple of points to consider:
Ground techniques and multiple assailants don't mix.
Speaking from experience most street fights do not go to the ground.
I'm not suggesting that an altercation that goes to the ground is out of the question just because I don't want it to happen that way. The truth is that I've invested many years in karate, a standup style, and the prospect of learning the ground at this point doesn't sound too appealing. I do have a friend who holds black belt ranks in Isshinryu karate, jiu-jitsu and judo (acquired in that order) who confides that if ever assaulted he would be inclined to fall back on his jiu-jitsu/judo skills, but that's him. Again, karate does include a variety of grappling-like skills that are highly effective in a standup fashion.
Karate, like most martial arts, were developed on the premise that your assailant is most likely a brutish thug who has no idea how to fight. This is a pretty good bet, but if you run across some drunken smartass who fancies himself a grappler you may be in for a rough time. Or maybe not. Jim Advincula, who began his training in Isshinryu karate on Okinawa in 1958, tells a story of how someone stormed into his school one night demanding to know why grappling wasn't included in the curriculum. Only when the intruder received a hiza tsui (knee-strike) to the face after a failed attempt at a leg lunge attack did he understand. He was lucky, it could have been much worse. As the saying goes, God protects fools, drunks and children.