Starting Bo Nix was right call. But Broncos’ Sean Payton may have to defend it soon.

Bo Nix earned the right to start. And it won’t be long before coach Sean Payton is forced to defend his decision.

Hear me out. Six quarterbacks were drafted in the first round last spring. Nix was the last.

Three started on opening weekend. You know how many will face four straight head coaches who were former defensive coordinators? The list starts and ends with Nix.

Any idea how many first-rounders have run this gauntlet over the last five years? Zero. Arizona’s Kyle Murray battled three in the season’s first four games, posting an 0-3-1 record. The Jets’ Zach Wilson, now a third-stringer for the Broncos, went 1-3, among them a shutout loss to Denver’s Vic Fangio.

Nix’s September schedule has not thrown him into the deep end. It is more like he’s clinging to a floating door with Jack and Rose near the Titanic.

This does not mean starting Nix was a mistake. It means this choice increasingly requires context. Broncos Country, put your trays in an upright position and fasten your seatbelts because last Sunday was only the beginning of the turbulence.

Processing information quickly remains critical to playing quarterback. In Seattle, coach Mike Macdonald forced Nix into mental overdrive. Everything was hard because of the varied, inconsistent looks. Nix reacted to what he saw by throwing quickly — he was only sacked twice — but he looked rushed. Known for his accuracy and ball placement in college, Nix missed behind receivers, above them and forced two interceptions into double and triple coverage.

The arduous mental challenge affected him physically with his mechanics — drifting and throwing off his back foot —until he found some rhythm in the fourth quarter. It’s OK to like Nix and admit he did not play well. But be warned: It only gets harder from here.

The Steelers won’t trick up the game like the Seahawks, but Mike Tomlin boasts better players. Edge rusher T.J. Watt might be the best player at any position in the NFL. The Broncos must make plays for Nix or Watt is going to be using the quarterback’s shoelaces to floss his teeth. Two road games follow at Tampa Bay and New York. Buccaneers coach Todd Bowles is widely revered for creating pressure through basic and exotic blitz packages. And the Jets’ Robert Saleh, already on the Bunsen burner, will heat up Nix and lean on his aggressive one-gap scheme to attack him from all angles.

There is no reason to panic over one week. But all 0-1 teams are not created equal, especially those with rookie quarterbacks. Payton believes in Nix. However, he failed him by throwing 42 times at Seattle. If the team must be better around Nix during this treacherous first month, that includes the play-caller and the players.

It’s time for the Broncos to reacquaint themselves with an old weapon that fell into deep disfavor in Seattle — the forward run. It would be nice if the Broncos’ Javonte Williams and Jaleel McLaughlin used it for a touchdown and 120 yards. Nix can contribute with his legs, but he is starting because of his arm and brain.