No target yet for Whisky
Oscar Whisky winning at Aintree
(Healy Racing Photos)
With the four-time winner now out of the way, the Nicky Henderson-trained seven-year-old is joint-favourite with Willie Mullins' mare Quevega with some bookmakers for the three-mile contest.
Oscar Whisky appeared to have his stamina limitations exposed when only fifth in the World Hurdle last year, but Walters feels that was not necessarily the case.
He expressed his sadness at the news regarding Big Buck's but that no decision on Oscar Whisky's target will be made until after his next race at Cheltenham on New Year's Day.
"It's a blow to the game about Big Buck's, he's the top horse now," said Walters.
"It's too soon to say which way we'll be going, though.
"The way we came up the hill last week you wouldn't believe he didn't stay three miles in March. I think it may have had something to do with his fall at Ascot (at the start of last season), he got a right jolt there.
"He'll probably run on New Year's Day and we'll make our minds up after that maybe.
"He'll certainly have an entry for the World Hurdle, anyway, but if the ground was like it was at the weekend in March he'd run in the Champion Hurdle.
"We don't want to ask him to race over three miles if he's not a three-miler. Not many horses win the Aintree Hurdle three times and we'd be quite happy doing that.
"I'm really sorry for Andy Stewart (owner of Big Buck's) though, he's a friend of mine."
Owner Andy Stewart believes there is a "more than 50-50 chance" that Big Buck's will be able to continue his racing career next season.