He was going out of bounds basically so well out of the pocket. He didn't drag him down from behind but pulled on his jersey enough to make Purdy's knees buckle slightly. Apparently the way the rule is worded this is enough to warrant a horse collar penalty. Another penalty that has to be interpreted by the refs in the heat of the moment. Was borderline.
ARTICLE 16. HORSE-COLLAR TACKLE
No player shall grab the inside collar of the back or the side of the shoulder pads or jersey,
or grab the jersey at the name plate or above, and pull the runner toward the ground. This does not apply to a runner who is in the tackle box or to a quarterback who is in the pocket.
Note: It is not necessary for a player to pull the runner completely to the ground in order for the act to be illegal. If his knees are buckled by the action, it is a foul, even if the runner is not pulled completely to the ground.
Penalty: For a Horse-Collar Tackle: Loss of 15 yards and an automatic first down.
View: https://x.com/wcsportsx/status/1756839070201008453?s=20