The language of this rule is a little ambiguous at first, but in layman’s words, an offence can still be assessed a major foul (such as unnecessary roughness) on a turnover in which the defence also commits a penalty—previously, the offensive penalty was not applied. For example, Elgton Jenkins, a Packers offensive lineman, commits a facemask penalty against Aidan Hutchinson. Jordan Love threw an interception to Brian Branch. On the Branch interception return, Alex Anzalone receives a holding penalty. Previously, the Jenkins penalty was not applied at the completion of the return.
On paper, the modification appears to be rather easy, but there is a twist. The puzzling issue is that the opposite of this rule was already in place. The replay official could alter a completed pass to down by contact or out of bounds—which was already in the regulation. For example, Baker Mayfield threw an incomplete pass against the Lions in the Wild Card game, but his leg was actually down; this may have been challenged and overturned.
However, the replay officials were unable to change a down by contact judgement into a pass play. For example, if Jared Goff threw a 40-yard throw but was wrongly ruled down on the play by the on-field officials, it would not have been reviewable.
Notably, NFL Network insider Tom Pelissero tweeted on Monday that the NFL has increased the replay official’s authority to include overturning roughing the passer and intentional grounding. Last season, the Lions were victimised by a play in which officials made a glaringly inaccurate judgement on a Justin Fields pass attempt. However, these revisions were not included in the official NFL communication, so it is unknown whether they were accepted and implemented.