Complex sentence: Drew Bledsoe, Robert Griffin III, and Marcus Mariota are the only quarterbacks to achieve a perfect passer rating in their rookie seasons, with Mariota being the only quarterback to post one in his NFL debut.
Split into simpler sentences: Drew Bledsoe, Robert Griffin III and Marcus Mariota are the only quarterbacks to achieve a perfect passer rating in their rookie seasons. Mariota is the only quarterback to post a perfect rating in his NFL debut.