later echoed by teammate Mark LeCras. In July, coach Adam Simpson said Barrass was ready to play at AFL level, but noted the backline was "pretty settled" and it would be hard for the defender to claim a spot. After McGovern hurt his left hamstring against , Barrass replaced him in the senior side against in round 17 of the 2015 AFL season. On debut, he recorded 15 disposals and five marks. Simpson was happy with Barrass's performance, saying "it's good to get exposure in such a big game", and noted the side's scarcity of key defenders after Will Schofield injured his calf. Fellow backman Xavier Ellis praised his efforts to play on dual Brownlow medallist Adam Goodes. Barrass played two more matches to end the year; round 18 versus and round 22 against . Barrass missed the first half of the 2016 AFL season but replaced Eric Mackenzie in round 12 after the defender fell ill. In July he was named as one of West Coast's key players under 23 by AFL.com.au journalist Alex Malcolm. He retained his spot for the majority of the second half of the season, culminating in a 2016 AFL Rising Star nomination after a twenty-nine point win against Adelaide in round 23. Barrass recorded seventeen disposals at 94.1% efficiency, ten spoils and ten marks, six of them interceptions. He polled one Brownlow vote for the performance. Barrass said he had been galvanised by his previous match against Adelaide in 2015, when he had been outplayed by their forwards. He went on to play in his first AFL finals series, but only managed an elimination final after West Coast were knocked out by the . Barrass had eleven disposals and took six marks; his performance was rated a 6 out of 10 by AFL.com.au journalist David Reed, who noted he improved after a slow start on Tom Boyd and took several crucial marks. Post-season, Barrass won West Coast's Rookie of the Year award. Ahead of the 2017 AFL season, Fox Sports journalists Riley Beveridge and Ben Waterworth named Barrass 'the rising star' at West Coast and a 'lock' in their defence. He returned to pre-season training in improved condition after feeling 'pretty fat' near the conclusion of the 2016 season. Barrass signed a contract extension prior to the 2017 JLT Community Series, tying him to West Coast until the end of 2019. During pre-season training,