BoB arena is pretty active at ~400k SM and it seems I deal less with that kind of nonsense than I did +2m (although it still happens). It seems like it takes a minute or two to warm-up and put you in a lobby of sorts, you play about 10ish matches and then you might have to wait around again for a minute or so; or it throws you in a high ping match.
The matches I lost earlier were a batstaff/fog and he panicked a bit when I kept pressing on. He won in the end because of my hesitance to heal and latency tells me he's not done with his cast animation but it still goes off and I'm left with a 1/5th of a hit to kill him. He had to taunt at the end of course.
The other was an early match I played warming up and I got two-shot by what seemed to be a buffed claymore faith build. I became impatient and tried to trade the last hit with him, the game considered he hit me first (Even though we both died, I beat him earlier anyway).
The most annoying matches were both PVP "veterans", they had the second aura. One cast warmth and just stood in it with his shield up/dodging shield breaks, and healed up about 4 deaths worth before it expired and then I had to chase him around the arena while he tried to cast it again. The second guy attempted to estus chug 3 times, got me down to a sliver of health before I turned my back on him and also chugged before turning around and just managing to out DPS him when he attempted to heal again. I stood on his faded corpse and did the emptying the bottle animation repeatedly out of saltiness.
I did almost lose to an UGS, I haven't really seen those that often and if you roll in anticipation an attack still might catch you at the tail-end.