Sergio Garcia was seen arguing with R&A officials at his qualifier on Tuesday when he was put on the clock for slow play.
Patrick Cantlay said he sustained his minor injury while training, which is what led to his late withdrawal in the Quad Cities.
Ten golfers are within three shots of Daniel Wetterich's lead entering the final round of the 103rd Ohio Open Golf Championship at Westfield.
Chun began his playing career at Cal in 1997 and had served the past eight seasons as director of golf for the Bears.