The Pretoria-born star missed the back half of 2024 due to a serious shoulder injury. However, the eighthman bounced back for his franchise to feature in every Stormers match since January.
Roos' efforts - combined with injuries to Bulls duo Elrigh Louw and Cameron Hanekom - resulted in his call-up to the Bok squad in 2025. He came off the bench in the second stanza, making ten carries and winning a turnover in an impactful cameo.
Now, the Boks are down another No.8 following Jasper Wiese's four-match suspension. So when Roos was the notable absentee from the matchday 23 to face Georgia on Saturday, it raised questions about Roos' role in the squad. The Bok Brains Trust opted for Cobus Wiese behind the scrum.
Speaking to the press this week, Erasmus outlined his long-term plans for the 25-year-old.
"He trains well and does well for us," said the double World Cup-winning coach.
"We lost Elrigh, Ben-Jason [Dixon] at some stage, Duane [Vermeulen] retired, and Jasper is now out with a ban.
"We gave Evan eight or nine chances, and he's training well. We can see that. We also want to see how a guy like Cobus will do at No.8, because we think he has potential there.
"It's a long season. After four matches, the door is not closed for anybody. We'd like to see Cobus at No.8. We have a good feeling. He [Wiese] is also a good line-out option.
"Like anyone else, Evan is still in the mix, without a doubt. We never drop people from our team. I don't know if people don't want to believe it - we [want to] get 12, 13, even 15 or 20 caps into Evan over the next cycle before the World Cup. And if we can get 10 or 12 caps into Cobus.
"That is why we have a group of 46. We see it as us getting used to each other in training sessions, match situations, and different combos. Because you are trying to win under pressure, but you are also thinking about the future.
"And the more we try out different combinations and guys swapping in and out, we think we will become a better team."