Complex sentence: He's had seven years of experience under Bob Bratkowski's offense, which he is set to use to mentor rookie tight end Jermaine Gresham, and 2009 draftee Chase Coffman.
Split into simpler sentences: He's had seven years of experience under Bob Bratkowski's offense. Which he is set to use to mentor rookie Tight Ends Jermaine Gresham, and Chase Coffman.