This study thoroughly misses the point ... as highlighted by a single counter voice at the end of it.
"It's actually immaterial whether they commit more crimes or not because they commit additional crimes," Dykes says. "They are crimes that would not be committed. There are American citizens who'd be alive today if [unauthorized immigrants] were not in this country."
When your son or daughter, husband or wife, brother or sister, et al, is killed by an alien illegally in any country, a study like this is meaningless and not even relevant to the discussion. It's mixing apples and oranges. There are legitimate ways to enter (again) any country. Those who follow the rules are welcome with open arms. Those who cut in line are not.
It depends whether you define the "the point" according to the current political debate about immigrants.
Assuming they have no major errors, the studies should have their own well-defined point about the violent crime rate of illegal immigrants. As per your and @Dudicles' comments, that point is only a very small part of the wider debate about immigrants, and has nothing to do with many other reasons for people to object to taking them in. Clearly the study does not prove that you are wrong for not wanting them in the country for 100 other reasons.
Some people seem to accept or reject scientific conclusions based purely on their ideological stances - the flat earth lies down that road.
Just putting it out there for discussion - no need to shoot the messenger.