NFL coaches have failed on 20 of their past 21 challenges for pass interference this season, a trend that could discourage them from using the league's marquee rule change in 2019.

Overall, there have been seven reversals in 40 pass interference-related reviews since the start of the season, including those initiated by the replay official in the booth. But coaches have grown increasingly frustrated by their inability to get calls changed in what seem to be clear instances of a mistaken call. The most recent instance occurred in the fourth quarter of the New England Patriots' 35-14 victory over the New York Giants Thursday night.

Giants coach Pat Shurmur challenged a no-call on a play in which Patriots defender Jonathan Jones made significant contact with Giants receiver Golden Tate before the ball arrived. NFL senior vice president of officiating Al Riveron upheld the original call of referee Brad Allen's crew.

"[W]e see that replay doesn't overturn much," Shurmur said afterward. "So I am not surprised."

Earlier this week, Pittsburgh Steelers coach Mike Tomlin -- a member of the NFL's competition committee -- said he doesn't think "any of us have a feel" for what an overturned pass interference ruling would look like. He added: "I'm just being honest. I don't have any idea what I'm going to do moving forward because it appears to be a moving target."

This season, NFL coaches have challenged a total of 10 plays in which officials have called offensive or defensive pass interference on the field. None have been reversed. They have been slightly more successful in challenging plays in which a flag was not thrown, getting four of those 23 plays reversed.

But their recent inability to achieve reversals of any type -- the 1-for-21 streak began at the start of Week 3 -- could lead to fewer challenges overall. Coaches have only two challenges at their disposal for a game but get a third if the first two are successful. They lose a timeout if a challenge fails.

The NFL declined to comment on the recent reluctance to reverse pass interference decisions. The rule was implemented on a one-year trial basis in response to a missed interference call in the 2018 NFC Championship Game. All NFL replay decisions are based on whether Riveron sees clear and obvious visual evidence of a mistaken call.