Look for the part of the team's play that was extraordinarily poor.
Today that was the team's number of first downs, which was 13, and which is well below the league average per game. In the presence of a slightly better-than-average QB rating, an adequate YPA, a poor QB rating and YPA for the opposition, and a zero turnover margin, that says we simply couldn't extend drives, and didn't have the running game or the playmakers in the passing game (i.e., receivers) with which to do so.
The Panthers on the other hand had 20 first downs, which is around the league average, and extended enough drives to win, despite the other statistics noted above.