It depends on how you grade skill at pking. If you try and grade skill of of just the total number of pks someone has, then there is none, it's just time investment. That being said, there is a skill as to how quickly someone can get many pks, and how efficiently. Anyu rose to her high number of pks very very quickly, and though she did put decent time in, the efficiency in her pking was quite clear, which takes skill. There is also of course the matter of kill to death ratio.
Spar may be a bit more clear as to why it takes skill, but I wouldn't say it's the only thing, assuming the skill measured for pking is what I mentioned above.
That sums up my opinion in the matter.