Warnock, traded by Fremantle at the end of 2008, finished last season on a high note after having injury problems in his first year at Visy Park and spending much of last season in the VFL, with the Blues concerned about his attitude towards training.
Warnock was one of Carlton's best in the easy win over Greater Western Sydney in their NAB Challenge match at Canberra's Manuka Oval last Saturday, booting four goals and controlling the ruck contests.
"He has been the best-performed player in our pre-season, from the start of pre-season right though until now," Ratten told afl.com.au.
"He and (Michael) Jamison have stood out further than any other player and (I) have been really impressed with the way he has gone about it.
"I think he's taken some feedback on board. I thought his last six weeks in the season was fantastic. From a club point of view, we've seen why we recruited this player and this is what he can do."
During the pre-season, Ratten has noted the Blues needed to play with a harder edge this year and has vowed they will be more ruthless and uncompromising in their approach.
"I just think [in] our mental attitude and the way we go about our games we need to be a lot rigorous in saving a goal," Ratten said.
"Across the group we need to be a little bit harder and maybe a little bit more ruthless in our approach for victory and the way we go about it. So hopefully when they say 'Carlton were uncompromising; they wouldn't give the team an inch' … win, lose or draw, that's something we'd like to be spoken about after games."
Despite being eliminated in the first round of the NAB Cup late last month, Ratten has rated the Blues' pre-season as the best since he took over as senior coach in late 2007.
Ratten, in the final year of his contract, conceded the Blues needed to raise the bar after making the finals in the past two seasons.
"That's the next step for us is to win a final," he said.
"There's no doubt that the club's history has been built on success and from our side of things we need to make sure that we get finals success. It's important that we get that over the next 12 months and especially winning a final will be really critical."
Ratten is looking forward to the return of young star Matthew Kreuzer, who is on track for an early-season comeback after a knee reconstruction.
Kreuzer has played most of his football in the ruck, but the coach believes he is capable of filling various roles including ruck-rover or as a key forward.
"We can use Matthew to his strength, and that is to hunt the footy up and chase the ball, which he does extremely well," Ratten said.
He is also confident Bryce Gibbs will relish a permanent move into the midfield.
"I think Bryce has shown he has the versatility to play half-back, half-forward, middle, but we think he can really add to our midfield," he said.
Ratten believes the Blues' depth has been improved significantly by the addition of ex-Tiger Andrew Collins, ex-Cat Jeremy Laidler, and mature-age recruit Nick Duigan from the SANFL.
"I think our depth has increased, which I think [will] help us maintain our pressure in games," he said.
"It doesn't put players such as (Matthew) Watson and (Patrick) McCarthy under enormous pressure to come in and play straight up."
This season the Blues have revamped their coaching panel, with Alan Richardson, Gavin Brown, John Barker and Luke Webster joining Ratten as assistants.
"Richo brings what he learned at Collingwood, Essendon and at the Bulldogs," Ratten said.
"Gav [comes] from the premiership team at Collingwood. Johnny Barker in the last four years has been at St Kilda and Hawthorn, and Lukey has been at Fremantle, so the intellectual property that we've got from teams that have played in finals in the last couple of years is something that we're very lucky to get and the way they've conducted themselves has been outstanding."
