Matheny was submitted for a number of tests on December, at the Sports Concussion Program at the University of Pittsburg Medical Center to see if the symptoms had disappeared, but they had not. On December the 28th he tried to exercise and after his heart rate had been elevated he experienced the same troublesome symptoms for a day and a half, such as fatigue, memory problems and a tough time focusing and seeing straight. "This is not a shoulder, a knee or an elbow," Matheny said on a conference call. "We're talking about the brain. ... I didn't expect this. I don't think anybody did."

He is known as an excellent player, who gives 100% always, even in the trainings, where he used to be the first one to show up at the stadium sometimes at 6am in the morning.

Matheny played his last full season in 2005, it was his first year in San Francisco, and he was recognized with the NL Gold Glove Award for the fourth time. He owns a .239 career batting average with 67 home runs and 443 RBIs in 1,305 games for Milwaukee (1994-98), Toronto (1999), St. Louis (2000-04) and the Giants (2005-06).