Conley, who was a fringe All-Star candidate for Memphis, went down last Friday with a grade 2 ankle sprain, and while there was some hope that he could return for this one, the Grizzlies apparently decided to give him some additional rest, especially with Memphis traveling to Cleveland on Sunday night. This is a huge "win" for Atlanta given Conley's stature with the club, and it puts the emphasis squarely on backup Nick Calathes to deal with Jeff Teague on both ends.
In the case of Allen, the 32-year-old defensive stopper has missed the last 16 games as a result of a ligament issue in his left hand, and while he was only expected to miss 2-to-3 weeks initially, the progress has been slow in his recovery. With Allen out, Memphis isn't in terrible straights on the wing, but it's a safe bet that Kyle Korver will have some additional breathing room with the All-World defender on the sideline.
Overall, the absence of Conley is a huge one, and because that leaves Memphis incredibly thin on the perimeter, the fact that Allen isn't able to return is magnified. The duo of Courtney Lee and the aforementioned Nick Calathes were both asked to play 40+ minutes in the Grizzlies' last game, and with only Darius Morris (on a 10-day contract) behind them from a ball-handling standpoint, the Hawks should be able to take advantage in a big way.