Rooney celebrated his 28th birthday on Thursday on the back of another sensational performance for Manchester United.
Although the striker did not score against Real Sociedad on Wednesday night, he was responsible for the second-minute goal that has moved the Red Devils to within a win of the 10-point total Sir Alex Ferguson used to use at the benchmark to qualify for the last 16 of the Champions League.
Even Ferguson admitted Rooney was in electric form this season, and claimed earlier this week he would not have considered selling him had he been producing such high-class performances on a regular basis last term.
But, according to Carrick - a team-mate for both club and country - the scary thing is Rooney can do more.
"I am sure he is looking to improve," Carrick said.
"He's getting on, isn't he? But look at Ryan Giggs. What he did on Wednesday was incredible. He goes from not playing for a bit to finishing a game like that - it sets an example to everyone.
"They say you are just getting into your peak at 28. If Wayne wants to can carry on playing on for a long time yet I am sure he will improve - and he is playing well at the moment."
Even now Ferguson's stance towards Rooney has softened, it does appear the striker has been wounded by his former manager's words.
The former Everton man confirmed he has not spoken to Ferguson since the end of the season and has already underlined how much he is relishing being played in a forward role by new boss David Moyes.
Yet Carrick rejects the theory Rooney has got his focus back.
For he insists it was never lost in the first place.
"You cannot question his focus at all," the 32-year-old said. "As players, you have good spells and spells where it doesn't quite go for you.
"He is having a great one at the moment and I am sure it will continue for a long time."
Moyes could do with Rooney maintaining his form because, in much the same way as he did in 2010, he does appear to be carrying United at present.
That might not have been the case had Ferguson remain at Old Trafford and been able to make the big-name signing it appears he was targeting, with Cristiano Ronaldo the man in the frame.
Ferguson's former assistant Mike Phelan told a Scandinavian United supporters' club magazine: "If Sir Alex and (former chief executive) David Gill had still been the bosses, there would have been a star signing - one of the absolute best players in the world.
"It was something the boss talked about, and the owners and David Gill were also quite clear on doing it.
"There's very few of such players out there. I think it's clear to everybody who I'm talking about."
Instead, Moyes was only able to make one significant addition to his squad - Belgium midfielder Marouane Fellaini, who has failed to meet his £27.5million billing so far.
Fellaini is not on his own in his struggles, though, which is why United entertain Stoke having won just one of their four Barclays Premier League home games so far and trail early pace-setters Arsenal by eight points following three defeats in eight matches.
"The frustrating thing is we have had moments in certain games of when you think 'this is it, we're on the up'," Carrick said. "Then in the next game for some reason it doesn't go how you would expect.
"That is the challenge we face. "We have done well enough again, but then we have to on Saturday."
Nothing can be taken for granted, though, largely because an explanation for United's troubles is so difficult to find.
"It is tough," Carrick said. "You can look at the Southampton game last Saturday and say we really should have won.
"We were 1-0 up and had chances to score more. Then we concede from a corner. In that instance, you could say we can defend corners better but overall it is about fine margins and little details.
"In the past we have been good at getting on top of those things and seeing games out.
"I am sure we will do that in the games we have coming up."