Dwight Howard was initially reported to be unhappy and so the National Basketball Association (NBA) trade rumor mill has gone crazy. Howard has denied all the talk but that is unlikely to stop people from speculating that he could be dealt soon.

Howard's struggles is believed to be something similar to the time when he was with the Los Angeles Lakers. After years of being the top dog with the Orlando Magic, he found it difficult to play second fiddle to teams with certified stars.
He dealt with that behind Kobe Bryant and now it seems he has the same fate behind James Harden. Howard has denied it (of course) but all things are bound to change by the end of the season when he can opt out of his current deal with the Rockets.
Right now, it doesn't seem likely he will be dealt unless the Rockets do the inevitable. The team surprisingly fired Kevin McHale and are now reportedly looking for possible trade partners involving Ty Lawson.
The Miami Heat have been mentioned as a possible destination but it is unlikely that Pat Riley will give up Hassan Whiteside for him.
How about the Boston Celtics?
Well, it could make sense where he could be dealt for David Lee and Tyler Zeller plus some of their future picks. As far as the Rockets are concerned, the picks are perhaps the one with utmost importance as pointed out via ESPN.
The Celtics don't really have a clear star right now, so it could be Howard's calling. Lee has been doing his share but, apparently, not as dominant as what Howard brings.
But before that happens, the Celtics may want to look into the state of Howard. He did reveal that he had knee issues in last year's playoffs but did not undergo surgery. He continues to deal with them plus some back issues so Danny Ainge may want to go in depth in the event that the Rockets would entertain a trade.