Wentz was born in Rothenbach. In the 1980s and until 1990 he represented West Germany and belonged to the world elite in the decathlon. His most notable result was winning the bronze medal at the 1984 Summer Olympics in Los Angeles, California. At that event he scored 8412 points, his results for each of the events were 10.99s - 7.11m - 15.87m - 2.09m - 47.78s - 14.35s - 46.60m - 4.50m - 67.68m - 4:33.96 min.