The five-Test series was billed as the biggest test of England's swashbuckling approach to Test series cricket, which is built around an aggressive, fearless brand of batting.
Their bid to hand Rohit Sharma's side their first Test series defeat on home soil since 2012 got off to the perfect start with a thrilling win in Hyderabad, where Ollie Pope played arguably the best knock by a touring batter in India.
But that was as good as it got for the tourists as India won the next four to prevail 4-1 and deflate the 'Bazball' hype.
"Sometimes you can get away with things, but when you're exposed in the way we have been in the back end of this series in particular, it does require some pretty deep thinking and some adjustment to make sure we're staying true to what we believe in," McCullum told BBC Sport.
"If anything we got more timid as the series went on and that was because of the pressure that was applied to us by the Indian line-up."
England's batting was a major disappointment and they sorely missed Harry Brook, who withdrew from the series due to personal reasons.
McCullum said England would be a better side when they host West Indies for a three-Test series in July, followed by another home series against Sri Lanka.
"A lot of good will come out of this tour. I'm 100 per cent positive about that," he added.
"We will be a better cricket team for the experience, although it hurts a lot at the moment."
Tom Hartley and Shoaib Bashir were England's top wicket-takers and both impressed in their debut series, which could put Jack Leach under pressure as the team's preferred spinner.
"Jack will understand that himself," McCullum said of the left-arm spinner, who missed the last four Tests against India with a knee injury.
"It's a good place to be when you've got depth and different types of options. We've got to embrace that and there will be some challenging selections throughout the summer."
