We have great depth at PG (Irving, Smart, Rozier) and of course epic depth at wing (Brown, Tatum, Hayward, plus Smart, Rozier, and Morris to a degree), but I don't feel that we have great depth or even top end talent with our bigs.
Horford is legit, for sure, but after that? Morris is probably our next best big and he is really more of a swing (although as a bench big, he is fine). Tatum is a great player as a wing but I don't consider him a big, certainly not a good big; he is barely a swing. So after our one really good big, our kinda big swing, and our small swing that is really a wing, we have Baynes, Theis, Ojeleye, Yabusele, and Williams.
This is our team's weakest link. It may not matter because we are so good in other areas but this is certainly not a "strength" of our team. Consider for example if Horford get banged up and misses some games. Then our stable of bigs gets really really thin.