The Celtics just got a pretty powerful wake-up call

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It wasn't that long ago we were sitting back enjoying the ride when it came to the Celtics. Just about a week, to be exact.

Brooklyn Nets, go get James Harden. No problem. Danny Ainge has put the pieces in place for what was the first-place Celtics.

Now we are creeping into the final week of January with an entirely different feeling. And the punctuation for the anxiety came with the Celtics' 112-110 loss to the Sixers in Philadelphia.

Friday night we were reminded about the be-all, end-all existence of Jayson Tatum, who didn't play again thanks to COVID-19.

Feel-good story Payton Pritchard now has a hurt knee, having totaled six points since the return of Kemba Walker.

They can't stop Joel Embiid, who scored a total of 80 points in the two games vs. Boston.

For whatever reason, Brad Stevens can't get this team to play consistent defense.

The idea this bench can help pick up the slack has become a pipe dream. They are 22nd in the NBA in bench scoring. This time Jevonte Green played 20 minutes with minimal production. Jeff Teague and Tristan Thompson aren't delivering in the manner Danny Ainge sold us they will. Grant Williams. Semi Ojeleye. They have taken a turn for the worse.

And then there is the ongoing frustration of Marcus Smart, the likes of which is a whole lot more palatable with the presence of Tatum. On the surface, Smart's 20 points Friday night was valuable. But it was also a reminder that the other parts of his game -- particularly on the defensive end -- are far more important.

Maybe we are simply discounting to what level Tatum is the straw that stirs the drink on both ends of the court.

But make no mistake about it, the optimism for the 2020-21 Celtics is at an all-time low. It's the job of Stevens and Ainge to make sure it doesn't dip any deeper.