Miyao brothers might not tap to leglocks but you should definitely.
Recently two grapplers duked it out to awful results. The tibia broke when the heel hook was applied in the video below.
The heel hook is generally considered to be a very dangerous leg lock, with a high rate of injury, especially to ligaments in the knee. It is banned, except in advanced competition, in many combat sports featuring other leg locks such as Brazilian jiujitsu and Sambo. Where it is allowed, holding it for too long is considered a serious infraction.
(Video) Gruesome Injury From Inverted Heel Hook During MMA Match
Warning graphic video:
How To Heelhook Proof Your Knees – Bjj Eastern Europe
Earlier last year there was a similar incident.
In round 7 of the recent MA1 Challenge Qualifier, Ashley Wright sustained a break of the fibula and tibia while fighting off a heel hook.
Sloth Jiu-Jitsu: you can be slow and unathletic and still kick butt in Jiu-Jitsu.