It's a bit of a change for Cook, who has played a great deal of his rugby at second row. But his new role has seen him been involved regularly, as well as taking up a senior position within the Blues' leadership group.
The young back rower again starts in tomorrow night's clash with Italian side Zebre as the Blues look to make it back-to-back home wins.
And with Cook starting to adapt to senior rugby, he says he can't wait for each game to come around.
"I've been playing second row since I came into senior rugby but I spoke to Phil and he wanted me to push for six because he thinks I'm the right sort of size," he said.
"I'm really enjoying it at the moment. It's not a surprise - I've always been able to play six but it's Phil's decision and I'm happy with it. I've been involved in the first two games and it's a great honour."
The Blues started their season with a narrow away defeat to Glasgow before getting the better of Connacht at Cardiff Arms Park. They face another home fixture tomorrow, this time against Zebre, boosted by the return of British & Irish Lions star man Leigh Halfpenny.
"The first result didn't go our way but the performance was there - we could see the improvement from last year and we've had a decent start," said Cook.
"Connacht was a tough game in the conditions but we ground out the win whereas last year, it seemed to go the other way. The main thing is about performing well and getting those results."
Halfpenny slots in at full back against the Italians alongside Alex Cuthbert with Davies making six changes from the side which played Connacht.
Lewis Jones makes his first start of the season at scrum half alongside fly half Rhys Patchell, who currently stands joint-top of the point scoring charts in the RaboDirect PRO12.
A new-look pack sees Marc Breeze start at hooker with Matthew Rees among the replacements.
Wales international Lou Reed is named in the second row with Bradley Davies suspended for two weeks following a league disciplinary hearing in Edinburgh. Andries Pretorius will captain the team while Cory Allen features in the match day squad for the first time this season.
On the return of Halfpenny to the side, Cook said: "Leigh is a great player and will bring an element of confidence to the team - we're looking forward to him running out for the Blues on Friday."
Davies added: "We know we've got a quality young squad of players. The longer you're together as a group, the more effective you become and we're starting to see signs of that.
"At the moment, we want to win first and foremost and create opportunities. Our intent to play is very good but we have to be a bit more accurate in the final third to get the ball over the whitewash.
"We expect to win at home but Zebre are a much improved team. The way they played against Munster, they were pretty innovative and were 18-9 up at one stage so they are a threat."