Here's a graphic from the Washington Post
on Obama's enforcement record. They're not criticizing him for lack of enforcement—they're complaining that he's doing any enforcement at all.
And when they say "the vast majority of immigrants removed continue to be non-criminals" they mean that that illegals haven't been convicted in the US of major crimes—they're pretty much all criminals, that's why they're called illegals.
Below are some activities of Immigration and Customs Enforcement (ICE), the agency within the Department of Homeland Security with primary responsibility for enforcing immigration law within the United States.