Too late for Button to be champion – Daly
Irishman Daly, who contested formula one races until the early '80s and is now a commentator, has written in a book that the fact Button's career stagnated at Honda may mean he now never wins a title.
He said that when Briton Button, 28, switched from Benetton to Honda-powered BAR earlier this decade, he looked like a future champion.
"The team then faltered," he said in his book Race To Win, of which extracts were published by The Sun newspaper on Friday.
"Jenson will have lost the Hamilton-Kubica type of hunger-drive and sometimes it's hard to get that back," Daly, 53, wrote.
Daly also offers critical observations about many of Button's current F1 rivals, including championship contenders Lewis Hamilton and Felipe Massa.
He said Hamilton's "technical abilities" – as well as Williams racer Nico Rosberg's – will not yet be "fully developed".
Daly, meanwhile, questions Ferrari driver Massa's "mental capacity".
"When he runs out of capacity he flies off the road," he said of Massa.
Daly advises Heikki Kovalainen to stop trying so hard. "If his expectations were lowered he could develop to be superb in two years."