Berankis' coach said that it's not smart going to tournaments if you are not prepared well. Ričardas was ill during the Davis Cup matches so I guess he wants to get well and to have some time to get back in form.
Moreover, he is still in Lithuania, his flight to America is sometime next week.
. Didn't know he was ill, of course I agree with Balzekas, it makes no sense going to a tournament if you're not at 100% (and has less sense if tis tournament is not Davis Cup, or a Grand Slam).
Hope he recovers well and be ready to play in Delray Beach