[17] At the beginning of the 2016 season, Vlastuin adopted the #1 guernsey, worn the previous year by retiring former club captain and personal backline mentor, Chris Newman.

[2][35][26] Vlastuin was back to his best in that role, lifting his metres gained average from 20th at the club to third as well as his intercept possession count from 1.8 to 8.3, good for ninth in the whole league.

[8] After season-best totals of 26 disposals and 12 marks against North Melbourne in round 8, Vlastuin ranked second at Richmond for intercept possessions with an average of 7.5 per game.

[8][2] In round 10 Vlastuin was forced to play the second half of a match against St Kilda as a forward after Richmond full-forward Jack Riewoldt sustained a concussion mid-match.

[48] Following the bye Vlastuin was again prolific, notching 21 disposals, 10 marks, a goal and six coaches votes that also saw him named in AFL Media's Team of the Week.

[51] At the beginning of August Fox Footy analyst David King labelled Vlastuin "a Luke Hodge clone" and the "AFL's most prolific intercept marker across the half-back flank (in 2018)".

[8] Despite being unselected in the league's All-Australian squad, Vlastuin was named to the best 22 in The Age chief football reporter Jake Niall's team of the year, "in recognition of his rise to become an elite backman".

[55] Following the conclusion of the 2018 finals series, Vlastuin was named as a close miss by the Herald Sun's chief football writer Mark Robinson in his list of the 50 best players from the 2018 season.

[8][57] Vlastuin started the 2019 season with appearances in each of the club's two pre-season matches, though played only restricted game time in second due to minor soreness.

[8] The loss of All-Australian defender and teammate Alex Rance to an ACL injury in that match however, would force Vlastuin into a more defensive role that in seasons past, becoming responsible for negating oppositions teams' third forward.

[63] When all three members of Richmond's leadership group were ruled out from playing in round 4, AFL Media named Vlastuin the front runner to captain the side that weekend, though he would eventually be passed over for the role in favour of veteran Shane Edwards.

[70][71] Vlastuin returned to the side in round 9, playing a dual role as defender and midfielder while kicking his first goal of the year and adding 24 disposals.

[76][77][78][79] Vlastuin closed out the home and away season with a nine mark, 13 intercepts best-on-ground performance that earned him nine coaches votes and yet another selection to the AFL Media team of the week in round 23.

[84][85] Despite that recognition, he was left out of both the final team and even the squad of 40 players for the official All-Australian award and was identified by Fox Footy and the Herald Sun as one of the most notable omissions.

[86][83] In Richmond's qualifying final win over the Brisbane Lions at The Gabba, Vlastuin recorded a career-best 12 rebound-50s in what Fox Footy described as a 'damaging' performance as a ball carrier at half-back.

[97] The 2019/20 off-season retirement of fellow defender Alex Rance reconfirmed the need for Vlastuin to repeat his important defensive role of 2019, which he showcased by participating in each of the club's two pre-season matches in March.

[108] He returned to play his 150th career match against the Brisbane Lions in round 10, before being caught on camera allegedly groping teammate Mabior Chol during post-match celebrations in the club rooms one week later.

[112] In round 13, Vlastuin attracted a $500 AFL Match Review fine for allegedly staging for a free kick during a marking contest in the club's Dreamtime in Darwin win over Essendon.

[114][115][116] He earned four coaches votes as equal second best on ground in round 15, after which point he ranked first among all players in the league for total intercept marks that season.

[127][128] He then had what Fox Footy called an impressively clean performance with nine intercept possessions as one of Richmond's best players in a preliminary final victory over Port Adelaide.

[130][131] His contribution to the victory was limited however, forced to sit out most of the match after suffering a concussion following an errant elbow from Geelong midfielder Patrick Dangerfield in the opening minutes of the game.

[132][133][134] In addition to the premiership win, Vlastuin earned the Maurie Fleming medal for a third place finish in Richmond's best and fairest award, following a 20-game season.

[144][145] Ahead of round 4, Vlastuin underwent further scans that showed greater damage to the knee that was first known, and that would require minor surgery which would see him miss at least a further four matches.

[149][150][151] Vlastuin was used for periods of the second half of round 9's comeback win over Greater Western Sydney in an inside midfield role, in place of the injured Trent Cotchin and Dion Prestia.

[153][154] He is highly capable at playing as a spare defender, assisting backline teammates in aerial contests while they are directly matched up on an opponent.

[137] Prior to the start of the 2020 season, AFL statistics partner Champion Data rated Vlastuin in the top tier "elite" category among general defenders in the league.

[2] Vlastuin traveled to the Indonesian jungles of Sumatra in 2018 as part of Richmond's tiger conservation partnership with the World Wildlife Fund.

[162] Vlastuin's Surf Coast Shire home was subject to a suspected arson attack one day prior to the 2020 AFL Grand Final.