Okay let me explain how the ranking system works in Virtua Fighter 5 Ultimate Showdown, to the best of my knowledge -
You start out at 1st Kyu, which is Level 1. There are 10 Kyu ranks, and you level up quickly through these. You don't lose ranking points for losses, all you have to do is keep playing and winning and you'll keep levelling up.
Level 11 is 1st Dan, and it advances all the way up to 10th Dan at Level 20. You still don't lose points on losses, but it takes a bit longer to move up each rank as you go higher.
At Level 21, you hit "Hunter" rank, and all ranks after that are special names. Starting at Hunter rank you DO lose points for losses, but you can not fall below Hunter rank. If you make it to Level 22, which is "Raider", and you lose too much, you can get demoted back down to Hunter. I believe you have to be playing people of similar rank to gain the most points, too.
When you do matchmaking, you can set it to find people either by "close" rank (which is usually within 5 levels of you, higher or lower), or you can search for ANY rank. I am sure Dave was searching by close rank, and was getting all those scrubs for the first few streams. When he switched to Shun he actually did sort of stumble upon a good scrubkiller strat - that punch into low kick combo of Shun's, which lets you followup with an elbow attack when they're on the ground (if they don't tech roll). He ran into lots of people that just simply would not block that low kick, so he spammed the shit out of that string over and over on people. Call it dumb pigroach luck that he managed to get this far.
But upon making it to Hunter rank, now he's stuck - he's only playing people within like a Level 16-26 range, so at this point he's bound to start running into people that recognize how to block low since he keeps going for that string over and over, and once they start punishing that, he's lost since he has no idea what to do otherwise. He did scrub out some wins here and there (even beat a Level 23 Akira 2-1), but for the most part all he did was lose more than he won so he never made it past Hunter rank tonight, as now he's stuck at a level where people can mostly adapt to what he's doing.
Although he's not actually stuck since he's going to quit the game because of a combination of salt and low tips. You ducked playing GG Strive for this, Phil?