Sigh..this has been done to death on here, so i'll throw out my two cents and leave it at that. Plenty of the guys on here are just gonna say 'ineffective' no matter what.
McKrotty and even much traditional Japanese and Okinawan Karate was heavily influenced by the spread of Karate to mainland Japan, and the sport ranges that came about from that, where a downward block gets used for stuff like blocking a kick or a ridiculously exaggerated lunge punch.
If you get to learn Karate that is even remotely connected to the old stuff, you get to see that gedan uke has a really simple application, such as pulling down someone's guard hand to hit them. It ends up looking pretty different from the McKrotty version, it's a much smaller movement.. but it is the same technique. There are still people out there who teach the more functional use of the 'basic' techniques.
The 'block' techniques in Karate aren't very different from what is many asian arts, and some older western ones. If you look at FMA's, Silat, or even old bareknuckle western boxing for instance much of what is done is very similar..but Karate is very popular, and as such alot of what you find is going teach the tradtional stuff like this as mostly window dressing, or just a way to break a sweat.
Edited by Zach_Zinn (05/31/11 09:18 PM)