The technical reasons are clear. The white ball does not swing as much; Roy’s role is to attack, to exploit the early gaps in the field and that suits him well; a few failures when playing an expansive game is an occupational hazard readily accepted. In ODI cricket the best place to bat is usually at the start of the innings. That rarely applies in Test cricket. Look at the struggles of Warner and Bancroft as well as England’s desperate, recent searches to find someone to bat there. The best bowlers are fresh, the ball swings, the nicks carry and the slip cordon is well-populated.
source: theguardian.com