Like the Celtics, the Hawks run a lot of action, misdirection, and motion off the ball, but their bread and butter like most NBA teams is the pick-and-roll. They use it to generate mismatches with guards driving on slower bigs or bigs posting up on smaller defenders. For most of the season, Brad Stevens has opted to ICE the PnR with guards forcing the ball to the sidelines and away from the paint and bigs backing up and containing penetration. There are many variations to the coverage and the Celtics have thrown everything at the Hawks, but that's lead to a 1-3 record and a lot of questions on how Boston plans to contain Atlanta in the post-season.
The Hawks aren't exactly an offensive juggernaut with a 103.0 offensive rating, but they are 6th in the NBA in eFG% at 51.6%. They know how to get their shots and they make them. Many have predicted that this series is going to be a defensive slugfest, but Atlanta has done well against Boston's defense, particularly at Philips Arena.
It starts with their guards. Jeff Teague and Dennis Schroder are very similar to Rajon Rondo; both are better scorers than RR, but when they're attacking a defense, their natural instinct is to be a playmaker and passer first just like the former Celtic PG. Atlanta ranks third to last in points per possession from the ball handler at 0.73. Despite those numbers, Teague is fifth in the league in drives per game at 11.1 (for what it's worth, Isaiah Thomas is second at 11.7). Although Celtics fans might cringe at the idea of Teague or Schroder going one-on-one vs. Kelly Olynyk, it could analytically be Boston's best defense against the pick-and-roll.
But that's just one way to try and keep Atlanta in check. To alleviate some of the pressure off the front court, the Celtics have at times ridden the hip of the driving guard as he attempts to penetrate and probe the defense.
That usually prevents a drive or forces a bad shot, but the downside has been another mismatch created when the guard recovers to the big. Post-ups are considered the most inefficient offensive play in the modern NBA and Stevens could live with a few ISO's of Horford and Millsap backing down Evan Turner and Avery Bradley.
However, Atlanta could counter by keeping their bigs above the break. With Horford and Millsap shooting 34.4% and 31.9% from behind the arc respectively, they're able to effectively spread the floor and create driving lanes for Teague and quick wings like Kent Bazemore. We saw that a bunch a week ago when Bazemore went off for for 21 and Schroder chipped in with 15.
Ideally late in the shot clock, Boston can pressure up on the ball handlers enough to make them pick up their dribble and move the ball. The defense will have to rotate with them, but it will take away the inside out action that frees them up for wide open threes. The Hawks were 7th in the league in 3FGA's, but only 15th in 3FG%.
Don't be surprised in Game 1 if Brad Stevens elects to go small early. In that April 9th loss, Marcus Smart started the second half for Jared Sullinger and that lineup change sparked a 16-8 run to extend the lead to 12. It gives the Celtics the ability to switch all the picks like Golden State's Death Lineup and almost negates all the different options Boston has to choose from in PnR coverage. And if Boston can come out with the same intensity that erased Miami's 26-point lead on Wednesday, they could easily steal one of the first two games in Atlanta if not both.