This was the correct defensive call.
It was executed terribly.
12 drives in the last 6 quarters for the defense. 8 TDs, 2 FG attempts, and 2 Punts. 38.8% of the runs went for 4 or more yards. It comes down to the DL.
Against the Ravens in the first quarter the Ravens had 1 big run of 7 yards. Wes Horton and Colin Cole never touched the offensive linemen over them and let them get immediate releases on Kuechly and Klein. Then Cole engages an offensive lineman and takes an angle into the backfield. The running back had already reached the LOS, so this choice by Cole was wrong. Then Wes Horton fails to keep his shoulders parallel with the LOS and pursue down the line to contain the RB. He rounds out off the LOS, over pursues leaving a gap for the RB and then tries to arm tackle the RB. After this play alone both of them need to be replaced. They made 5 mental errors between the 2 of them on one play. It would have been better to engage the OL trying to get to the line backers and push them down the line with their momentum in the gaps for the RB. This frees up the line backers to make the play.
The biggest issue is offensive linemen are able to turn Stars shoulders way too quickly and ride him out of the play. This is what the Steelers exposed and the Panthers will see it time and time again until it is corrected. Turning Stars shoulders so quickly means he can now be single blocked and the other OL helping to turn Star now has a clean release to Kuechly. This DL went from a force to a joke in 6 quarters of football.