I know somebody probably mentioned it already in this 100-page thread, but giving Hayward an extra two days to decide on his option really screwed us over. Two days is a lifetime in communications and planning, especially in the accelerated draft and free agency period this year. This is a courtesy they had no freaking reason to give Hayward considering he had months to think about it. Why would they have done it, other than in the expectation that keeping Hayward happy would either A) make the relationship smoother if he did indeed opt in and stayed in Boston or B) keep the good feelings going for participation in a sign and trade so we at least didn't lose him for nothing.
I'm not a person who thinks Hayward "owed" us anything for being injured and having overall disappointing play these three years, but I do think it was ridiculous to ask for the extension and even more ridiculous for the Celtics to grant it. Maybe it wouldn't have changed anything and Charlotte still swoops in with big offer the Celts didn't seem to anticipate, but I just can't think of a similar scenario where a team that already knew they probably weren't going to re-sign a guy conceded to his dithering and allowed him to delay during the two busiest days of the NBA calendar.
How? I assume that, if they hadn't given him the extension, he would have just opted out. That 2 extra days gave us more time to find a trade where he would opt in, but it didn't hurt us in any other way.
Teams couldn't talk to him during that time. The deadline for players opting out (Hayward included) was more than 24 hours before free agency began. All it did was push his deadline from pre-draft to post-draft.