Approximately jack.

But here goes:

1) As KC said: WC groundfighting and grappling is non-existant for many lineages;

2) Situational problems can and often do come up, as may have been the case here;

3) So-called masters can (and may have had here) bad days.

4) Wingchun sucks

If you watch a lot of NHB type fights (and I have) they often look messy and lacking in style. So no, Rogue, I didn't see (m)any WC principles in this mess, but I have seen (just one eg off the top of my head) a good Muay Thai guy get a shin kick in his eye from a good BJJer. He responded by doing what looked like a BJJ throw. So what?

No, I haven't seen any WC fighters in the ring.

No, I haven't seen any vids of it in action.

I have seen and unfortunately participated many real-life altercations (before I started WC) and have been forced to use (the tremendously inneffective ) aikido and karate in them. What I did almost certainly didn't look like aiki or karate. So I could say I believe, on this experience that WC offers some solutions to self-defence situations.

Is it useful in MMA ring/cage fights? I don't give a ****!!!