Paul Millsap was spectacular, the Hawks were playing their brand of top-drawer defense (excellent first shot defense, some occasional slippage when the opposition grabbed offensive rebounds), and they were in good shape to survive the dreaded joint indecisive performances from Jeff Teague and Dennis Schroder*.
*Upon whom it is now clearly established to be open season.
The Hawks were up 13 points with 6:33 left in the third quarter. Mike Scott entered the game and was a complete disaster defensively for the next 6:33. Marcus Smart's semi-transition layup at 5:33 was due to Scott panicking and forcing Kent Bazemore not to pick up Smart in transition. Scott could not stay in front of Smart on the downhill, natch. Jonas Jerebko's two threes - at 1:23 to cut Atlanta's lead to 8 and at 0:20 to cut Atlanta's lead to 3 - were both directly attributable to Scott losing all contact with Jerebko at the first opportunity.
Scott wouldn't play again, but it was game-on at that point, enough for the short-term variance of the Celtics making slop (Marcus Smart's two threes, Isaiah Thomas banking in a 15-footer he threw up at roughly 19-foot weight from the top of the key) while the Hawks missed high-percentage shots (Horford missed a jump hook on the block, a wide-open corner 3, plus wide-open, spot-up 15- and 19-footers, Korver missed both his threes) in the fourth quarter. Said variance then made meaningful Teague dribbling out the final 15 seconds of a tie game in regulation, and the Celtics thoroughly outplaying the Hawks in overtime.
For the glass-half full types, perhaps the Hawks combined the Teague/Schroder dual dud and the lack of quality depth potential losses into a single L. For those inclined toward pessimism, the Hawks just dropped a pair of winnable games against a shameless bunch to reduce their chances of winning the series to home-court advantage over a three-game sample size.