Williamson joined the AirHogs last season notching a win and no losses in three starts. In 18.2 innings pitched, Williamson finished with a 2.89 ERA with 10 strikeouts.

Before his late season arrival to Grand Prairie in 2009, Williamson spent the first part of the season with Shreveport-Bossier of the American Association, going 8-5 in 15 starts with a 4.92 ERA and 61 strikeouts.

Williamson was selected by Chicago White Sox in 27th Round of the 2004 MLB draft and stayed in the White Sox farm system for three seasons. Since then, Williamson has spent three seasons in independent baseball.