Here's some stats for you. If we consider our top-7 guys IT, Al, AB, Jae, Amir, Smart, and KO, here's the breakdown of games played without them.
Games without one top-7 guy: 15/23 or 65% of our games
Games without two top-7 guys: 11/23 or 48% of our games
Games without one starter: 11/23 or 48% of our games
Games without two starters: 8/23 or 35% of our games
It's hard to develop continuity and chemistry with that many injuries, especially when one of the guys is Horford, who is new. And you absolutely must have continuity and chemistry when you're facing a team that has move pure overall talent, such as the Raptors, Spurs, Cavs, Rockets, Warriors, etc.
Look, there are certainly weak areas that we have, like rebounding and over-reliance on threes. But it is incredibly way too early to make any definitive declarations about the ceiling of this team with as early as it still is and with as many injuries to key rotation guys that we have had. Our defense for the most part has been much better the last three games, and we've shown flashes of how good we can be when we're fully healthy.
So take relax and take a deep breath. It was always a long-shot that we would win this game without IT.