I would be all over bringing Howard here.
He's on a very reasonable contract for a guy who just finished the season averaging 13.5 points (on 63% shooting) and 12.7 rebounds.
His rebounding ability, ability to draw double teams, and sheer physical presence is exactly what this team needs.
Regardless of whether Horford likes him or not, Howard's ability to dominate the paint (and draw double teams) would leave Horford (and the rest of the Celtics) with open jumpers all night, every night.
That's exactly how Dwight was able to be so successful in Orlando - he was a monster in the middle and was an automatic double team, so they just gave him the ball and surrounded him with shooters. Somebody always ended up open, and all they had to do is make the shot.
The biggest reason we lost game 1 and 2 in Chicago was that we got smashed on the boards. One of the biggest reasons we got down 16-0 today is because we got smashed in the paint.
We got lucky enough to be able to ride the Kelly Olynyk random rainbow of beastliness back in to the game, otherwise this game could have been really ugly.
If we had a Howard / Horford frontcourt then we probably would have swept Chicago. Even the Wizards strong frontcourt would have nightmares trying to defend a Howard / Horford front line.
People tend to talk about Howard as if he's washed up, and is no longer any use on offence. People are completely oblivious that he put up just as many points for the Hawks this season as Horford did for us, Howard just did it a LOT more efficiently while also grabbing twice as many rebounds.
Dwight is stil a legitimate two-way big many while also being one of the greatest rebounders ever to play the game. His potential impact should not be underestimated. A team like this (ranked 1st in the playoffs in three pointers made, but lacks rebounding and physicality in the paint) is the perfect fit for Howard's game.
Howard is basically a more experienced Andre Drummond, or a "super Perkins". If you liked what the 08 Celtics looked like with Garnett and Perkins, then you'd like what the current Celtics would look like with Horford / Howard.