When you say that someone is ill, what you are implying is that the individual is not well right now. At the moment, he is ill; you don’t know whether he was ill 15 or 20 minutes ago. The only thing you can be sure about is the fact that he is ill right now. `Has been ill’ suggests that the individual has been unwell for some time. As to how long he has been unwell, one can’t really say. The construction suggests that the individual was unwell sometime ago, and still continues to be unwell.
*The players are in Hyderabad. (Right now, the players are in Hyderabad)
*The players have been in Hyderabad. (They have been in Hyderabad for a while)