when big players creates speculative position then *TRADED VALUE(the value of the total no of shares traded) increased but delivery % decreased..at the end of the day if you check delivery % decreased but traded value increased that means big players not interest in cash buying .. thats why delivery% decreased ..
when they creates this type of activity implied volatility increased because they also hedge their position using option..
if they play in intraday with heavy lots then it will not so easy to sqroff the trade same day ,then how can they book profit?? Stock/index should move 5/6% then they can earn 2/3%..
i hope your doubt is clear.