Just look at vintage Mike Tyson's fights on how he would rip those viscous uppercuts, and leave his opponents unconscious. Remember Holyfield vs. Cooper, Evander's uppercut couldn't miss that night, and it was truly damaging to Cooper.
Great fighters know what this punch can do, and what it can add to their offense. Why it's so underused by many fighters, I have no idea.
The key to throwing the punch, is dropping down, and driving up with the leg's. The uppercut is not an arm punch. When you drop down and rip up with it, your throwing it right.
You use some trunk rotation when throwing the punch too. Yes you use your arms to throw it, but more so at the finish of it. That's where the ripping part comes in.
If you get lazy and sloppy with the uppercut, it can leave you open for a counter punch. The counter punch thrown, is often a hook that can knock you out.
It would be wise for you boxers to hone this punch in your training. You can then perfect it in sparring. Leaving you to enjoy what it does for you, in your matches.
If your a boxer, it would be wise for you to hone this punch in your training. Next, perfect it in your sparring. Then watch how it ends fights for you quickly, in your matches.