Well think about it - in Cricket, you spend weeks and/or months away from home in a country that, more often than not, is worse than your home country (in fact, near as I can tell, the only test sides that are close to England in terms of culture, living conditions and so on are South Africa (maybe), Australia, and New Zealand). That's going to take it out of you, particularly if, as I believe is the case with Yardy, you're a young, inexperienced player who's probably on his first tour with the A-squad, which involves meeting new players, probably for the first time in anything other than a "Hi, bye" sense. That's going to be stressful for anyone.
Yardy's toured before (he helped win the 20:20 World Cup in the West Indies for starters), but the sub-continent is a tough place to tour. Players live in a cocoon and it must be a novel experience for him to be an instantly recognisable star out there when he's largely anonymous even around Hove.
On a slightly pedantic note, I should also point out that England's culture can't be similar to Australia's, on account of the fact that Australia doesn't have any culture.
Other than bacterial culture.