#1 D2 player would probably get crushed by the #125 D1 player. However, D2 & D3 do have some competitive players at good schools such as Johns Hopkins and NYU and others. Some of their recruits could get a D-1 scholarship if they really wanted to.
There are exceptions to this. For example, a few years ago the top player in D2 was a guy that came to the states with an ATP ranking in the 600's. He was plenty good enough to be a very high level D1 player. Sometimes it's easier to slip a guy through at a D2 or NAIA school that may have "questionable" eligibility status.