NFLPA president J.C. Tretter calls for all of league's turf fields to be converted to natural grass
NFLPA president JC Tretter calls for turf ban amid rise of injuries
Browns center, NFLPA President JC Tretter wanted to make sure players had option to opt out
Browns starting center Tretter returns to practice after surgery
Artificial turf vs. real grass: NFL's ongoing problem with playing surfaces
NFL news: NFLPA prez speaks for switch to teams using natural grass
Cleveland Browns' JC Tretter re-elected as NFLPA president
J.C Tretter: 'Only Natural Grass Can Level The NFL's Playing Field' - Sports Illustrated Cleveland Browns News, Analysis and More
JC Tretter makes retirement decision amid blackball speculation
NFLPA president JC Tretter urges teams to use exclusively grass fields - Sports Illustrated