Is this an example of chaining adjectives? I came across this sentence in my reading yesterday and even though I didn't quite understand the grammar being employed I decided to skip over it because I understood the gist of it, but I've now decided to return to the issue because skipping over issues defeats the purpose of my reading. The sentence was, "...， 没来得及避开的很快就被骷髅们蜂拥而上，撕成碎片。" which I understood to mean:

　　　　　　　　　　　　　　　　⤚--------------------⬎
没来得及　　-　not having enough time to  ____ 　¦
避开　　　　-　evade　----------------------------⬏　　¦
的　　　　　-　[having the property of]　----------↵
很快　　　　-　[also] is quick
就　　　　　-　immediately
被骷髅们　　-　by skeletons
蜂拥　　　　-　swarmed
而上　　　　-　over [a certain point]; excessively
，
撕　　　　　-　torn
成　　　　　-　turned into
碎片　　　　-　pieces


The completed English being, "[those who] were quick but lacked enough time to evade were immediately swarmed by skeletons in excess and torn into pieces."
The part I had difficulty with was "没来得及避开的很快". Is this a simple case of chaining adjectives? Because I can't make sense of this otherwise. And if so, is speaking (writing) like this normal? 

It sounds goofy to first declare that they weren't quick enough to get away, and then follow up by calling them quick. I found on this answer that when listing adjectives any adjectives ending in 的 should be placed first. Is this something that I should just get used too?

Additionally,  I could not find an entry for 而上 in any of the readily accessible dictionaries I normally use, I had to make a trip to Baidu to just barely understand what this means, did I use it correctly?
The sentence should be understood as such: 
[没来得及避开的] 很快 就[被骷髅们] 蜂拥而上，撕成碎片

没来得及避开的: the ones that don't have enough time to evade. 

很快 is an adverb soon, quickly. 

就 denotes something happens very soon. 

I tweaked your understanding: 


  those who didn't have enough time to evade were soon/quickly swarmed by skeletons in excess and torn into pieces.