What was John Fox thinking with Mitch Trubisky?

Final NFL preseason games are usually about players 50 through 53 on the roster. But long before the Bears took the field on Thursday against the Cleveland Browns, the great debate in Chicago was all about rookie phenom Mitch Trubisky and the decision to start him in a meaningless curtain call.

Trubisky made it through the start OK; it was the end where things got very strange.

The Bears had Trubisky hand off nine times to begin the game, much to the dismay of the Soldier Field crowd. Later in the first quarter, they let their No. 2 draft pick throw a few passes. Then, with a nod toward the future, they wisely took Trubisky out and let Conor Shaw do the mop-up work in a 25-0 loss.

Only problem was Shaw got hurt late in the fourth quarter. Not once but twice.

Trubisky went from being relaxed and joking on the sideline with the other Bears backup quarterback, Mark Sanchez, to being thrown into the final plays of a game where fourth-stringers are trying to make one last impression to coaches before the Saturday cutdown. Not a good time to take your franchise quarterback out of bubble wrap, especially against a defense taking orders from Gregg Williams — yes, he of Saints’ bounty fame — that already had been called for a late hit on Trubisky.

To make matters worse, as the final seconds were ticking off the clock, Bears coach John Fox decided to use his final timeout with 11 seconds remaining and his team facing a third-and-four from the Browns’ nine.

No problem, hand off and end it, right? Nope.

Trubisky threw an incomplete pass.

Six seconds to go. OK, now hand it off. Right?

Sure enough, Trubisky dropped back to pass, and jersey No. 10 quickly disappeared under two Browns defenders who probably won’t make it past Saturday.

Trubisky walked off after the game-ending sack, but the odd scenario left fans and media shaking their heads.

In his condescending, I’ve-coached-in-two-Super-Bowls tone, Fox said after the game: “I think it’s fair to say it wasn’t the first time he’s been hit, and it won’t be the last.”

Trubisky joked about it, saying it reminded him of his red-shirt days at North Carolina. “Come off the bench cold and play football,” he said. “That’s about it. I wish we would have scored.”

“Anytime you go out there, it’s a risk, truth be told,” Bears coach John Fox said. “Football is a rough game, no doubt. You don’t want to see people get hurt, but it is part of the game. I don’t know if we exposed Mitch a whole lot, but I can also say anytime you trot between those lines you are exposed.”

The nonplussed Fox doubled down on the bizarre ending: “Anytime you go out there, it’s a risk, truth be told. Football is a rough game, no doubt. You don’t want to see people get hurt, but it is part of the game. I don’t know if we exposed Mitch a whole lot, but I can also say anytime you trot between those lines you are exposed.”

Yes you are. As a coach, too.