KANSAS CITY, Mo. — Through the first eight weeks of the NFL season, Denver Broncos’ head coach Vance Joseph made it very clear Trevor Siemian was his team’s starting quarterback.

That was until Monday night when the Broncos fell to the Kansas City Chiefs 29-19 to fall to 3-4 on the season.

“I’m not sure. I’m not sure,” Joseph said when he was asked after the game if he will change quarterbacks this week. “But losing three games in a row and having five turnovers tonight, anything’s possible.”

Three of Denver’s five turnovers on the night came at the hands of Siemian, who finished the night 19-for-36 for 198 yards with one touchdown and three interceptions for an abysmal passer rating of 43.5.

“I’m going to watch the film tonight and tomorrow—like most coaches would do—and see,” Joseph said when asked how he’ll decide if he’s going make a change at quarterback. “Tonight, our defense played winning football, in my opinion. Our offensive line blocked—we ran the ball for 177, and the pass-pro was better. But it all comes back to turning the ball over five times, that’s insane.”

Along with “insane,” Joseph went on to add the turnovers were “mind-boggling” and “unacceptable.” While Denver’s 19 points were more than they’ve scored since Week 2, they’ve still only averaged 12.2 points per game in their last five outings.

In Joseph’s eyes, it all comes back to the turnovers.

“We have to fix our problem of giving the ball away,” he said frankly after his team dropped their third-straight game in a row and four of their past five. “We’ve got to fix the issues on the offensive side of the ball to keep our team having a chance to win.”

The biggest catalyst to the turnovers has, in fact, been No. 13. In the past five games, including Monday night, Siemian has three touchdowns to eight interceptions.

While it’s uncertain who will replace Siemian under center moving forward—either Brock Osweiler or Paxton Lynch— Joseph made it very clear that his unwavering commitment to Trevor Siemian is no more.