The Celtics have the NBA's best record by the all star break but just 1 all star, Kyrie Irving.
Horford's scoring will drop low enough that he won't get in. Hayward's personality along with being presumably rusty suggests to me that he won't score enough to get in despite the name recognition. Then Brown and Tatum would both need to have great first half numbers to make it and neither will score enough. Basically, shots will be too evenly distributed to justify another all-star.