Taking a risk working with a new professor? (Math Grad School)
As valuable as your professional connections and mentors are and will be in your career, please do not rely on other people or university rankings to shape your oncoming accomplishments. The responsibility in how successful your future in research will be depends on you-- how well you understand theory and can apply it, which academic and career risks you're willing to take, and the quality of the relationships you cultivate in your field. You may want to also consider more than just the potential mentor's Rolodex and publications portfolio. Is he/she professional? Genuine and authentic? Veracious? Objective? To help you make a better choice, what-if this-- if the person (that you described above) were you post-PhD, would you want you to be your chair? Much success to you.