Grehan is among the six GB&I players with previous Walker Cup experience, while Whaley is one of four rookies competing in the match for the first time.
“Stuart [Grehan] has been great. Having great experience at Lahinch, winning The Amateur Championship, and being the local home player, he has naturally taken on a leading role," Robertson added.
“He’s been galvanizing the first-time players, and he’s really excited for the week ahead.”
Whaley is among the players experiencing the Walker Cup for the first time this week, however Robertson doesn’t see him as having any less influence than his GB&I peers.
“We have five two-time Walker Cuppers, plus a 19-year-old playing in his third Walker Cup [but] even our debutants don’t feel like rookies,” he said.
“There are leaders within the team, and they are playing a leading role, but everyone within the team has a responsibility within that.”
Robertson added: “Jack [Whaley] is someone I’ve gotten to know closely day-by-day, and he’s a fabulous golfer and person.
“He is refining his skills for the test ahead, and I’m really excited to watch him perform this weekend.”