Sorry to say, but your proof is flawed.

To start, 3 random games does not present enough information to support your claim. Additionally, you said they were games you just had, meaning they are all the same map. It could be possible the Ninjas fair better on that map but poorly on others. You'd need data from all the maps to compare, and lots of it.

Also, the kill count it calculated once the target dies; so it is possible they were just lucky enough to deal the final blow. Plus player skill is very important. It's entirely possible that the people not on Ninja were just bad, and those on Ninja practiced until their fingers bleed.

Lastly, you may not realize it, but you are skewing the data, or in a sense hiding important information from us. I don't think it's intentional though. Based on the information presented in the images we can see you were on the Adders for the first two and the Flames for the third. But we don't know what teams the Ninjas were on. Now by default, PvP doesnt show names of anyone from the other teams, just those on your team, it only shows their initials. By not knowing what teams they were on, we can't get a feel for whether they were acting solo or collectively with their team.

They could appear to be OP, and the skills you pointed out could be an issue. But unless clearer data is presented, it's just an inference based on personal experiences.