The pilot stated that he was conducting his second stop-and-go landing when the airplane touched down with a "very slight bounce." After the airplane settled back onto the runway, it began "pulling" to the left. The pilot stated that he applied right rudder, but the airplane's response was "slow," and the airplane departed the runway into the "wet and muddy" grass. As the airplane decelerated, it nosed over and came to rest inverted. The airplane sustained substantial damage to the vertical stabilizer. The pilot reported there were no mechanical malfunctions or failures; nor were any discovered when a Federal Aviation Administration inspector examined the airplane following the accident. The weather reporting facility at the accident airport reported winds from 020 degrees at 6 knots about the time of the accident.