That constant forward energy meant that, the second a weakness was found in the opponent's guard; the attack would press forward hard and fast. (Very much mimicking the fast bursts that make up real violence... not sport).
Obviously it sounds like this group was a minority in how things are commonly done. I can only say that my 20+ years of MA experience and learning was impressed.
I think this is the key to the wing chun sparring mentality, in fact - as Tony Ferguson demonstrated against Pettis in UFC - you just have to have the confidence (and thus relevant training level!) to constantly press forward and 'box them in' in order to force your opponent into a pressured spot and make them lash out in desperation.
It is not 'rushing in' hoping for the best, though. Instead, it is calmly, methodically, plodding forward in a grounded fashion towards the target with a 'long guard' (better if one has reach advantage, of course, otherwise one needs to be speedy to get into the pocket), but very few wing chunners seem to practice this
very much wing chun philosophy attitude/approach in sparring.
The biggest issue, however, for wing chun in sparring/competitive MMA is that the power move is really the elbow, and not even Muay Thai spar their elbows effectively - THEY say that "it is just too dangerous" to do that, just like wing chun practitioners will say (but for some reason they are sniggered at, whilst muay thai stylists are not).
The K.O. power cannot come from wing chun fists in sparring/MMA sport fighting - those WC fists are sent out to distract and judge distance - to create openings for a speedy entry or another technique - to get into close range and to deposit the elbow 'payload,' for example.
So in fact, the wing chun sparring 'style' ends up looking a lot like muay thai - and this is probably why, for example, even though Tony Ferguson trains the elbows he finished Pettis with on a wing chun dummy, MMA fans (like Rokas) will not recognise wing chun's potency in the UFC cage - they will swear that Ferguson was doing muay thai.
On the street, however, the wing chun straight strikes such as cannon punch can aim for the throat, and come into their own in that respect. And if a strong umbrella is to hand, the knife form straight jabbing stuff can even be used. Wing chun ultimately revolves around straight line strikes from long knives and spears. Empty handed, however, then it needs to generate power from elbows, really (as a woman would), and so in sparring ends up looking like Thai kickboxing :/ . Not a problem, really, but elbows just can't really be effectively sparred outside of light sparring level, and even then it feels pathetic and pretty much useless to try.
Again, this stuff is made clear to Rokas, but he seems to be ambivalent. Perhaps it would generate less youtube clicks.