Low Nameless Monster walks a lot more, and teleports a bit?

Nameless aggro was probably on whoever was dealing the most dmg so you kept losing pin. Kind of like how rush doesn't work if someone else hits first cause the aggro is fixated on that other person temporarily.

To maintain pin successfully in nameless you need to make sure you're whiting. This is to make sure nameless' aggro is on you and you only. You'll occasionally lose aggro every now and then for some strange reason but you will have it pinned no issues whatsoever 99% of the time as long as you're whiting.

 

It's then likely due to the frequency of his attacks. Skull without SI is insanely slow and the buffer period between hits probably allows nameless to switch aggro and do wanky stuff.

OP i suggest retrying this with SI and see if you see the same effects. The main difference between a mage spamming CL and this video here is that CL is casting at roughly twice the speed as skull without SI

 

Said bucc is probably going to destroy your pin with barrage but you can test it when he's in ST

 

Nameless rubber banding like that reminds me of when you throw a wrestler at the rope but they bounce back and clotheslines you.

 

I also found some weird wonky behavior when you reach the 50k threshold, but your attack isn't fast enough (CL), so you don't really pin it. So in my solo's, it just keeps attacking non-stop. But when you're playing with a BM, suddenly it stops attacking, and does like 10 attacks the entire run. Nameless is just a weird boss...

Also, I imagine the pinner (paly or IL) usually whites among a party of similar leveled people, because having 1.5x damage is busted...