Despite nearly constant speculation about his place in the Test team, Siddle was the only Australian bowler to play all ten Tests across the 2013 and 2013–14 Ashes series against England, bowling reliably throughout the two series. At Trent Bridge, in Australia's first bowling innings of either series, Siddle took figures of 5/50 to help bowl England out, proving his value to the team. But his form waned towards the end of the season and he only took one wicket across the last two Tests of the series, which Australia lost 3–0. Again, there were critics who blamed Siddle's poor form on his diet and Siddle continued to deny that his diet had anything to do with his poor form.