John Fox doesn't rule out making change from Mike Glennon to Mitchell Trubisky

— -- LAKE FOREST, Ill. -- Chicago Bears?coach John Fox on Friday didn't rule out making a quarterback change from Mike Glennon to Mitchell Trubisky, even as he admitted to being purposely vague with the team's next game 10 days away versus the Minnesota Vikings on Oct. 9.

"I'm not really trying to be clear [about whether Glennon is still our starter]," Fox said. "Actually, quite the opposite. But we're evaluating every day."

Fox quickly reaffirmed Glennon's position atop the quarterback depth chart following his disastrous, three-turnover game at Tampa Bay in Week 2, but the same vote of confidence did not come Thursday night, when Glennon turned over the ball four times in Chicago's ugly 35-14 loss at Green Bay.

"We need to make a lot of changes," Fox said after that game. "We will evaluate everything, and we've got a lot of work to do before we line up against Minnesota. We are going to look at everything."

According to Elias Sports Bureau, Glennon is the only Bears player in the past 40 seasons to have three turnovers in a half twice within the first four games of a season. The Bears have lost three of four games with Glennon at quarterback.

Fox said Friday that Glennon's contract -- the quarterback earns $16 million guaranteed in 2017 -- will not factor into the Bears' decision.

"I don't think so," Fox said. "I go way back to when I came in the league. We weren't even allowed to know what a guy made because we didn't want that to influence the decision. I'm just kind of old school that way. I just like to evaluate people based on performance."

Trubisky -- drafted second overall in April -- won Chicago's primary backup job in Week 1, beating out veteran Mark Sanchez, who has been inactive the first four weeks.

Trubisky sparked the Bears' offense in the preseason, passing for 364 yards, three touchdowns and zero interceptions for a 106.2 passer rating, but questions persist about his readiness to take over the Bears' offense full-time after starting only 13 career games in college at North Carolina.

"Until that happens, you don't really know [if a player is ready to start]," Fox said. "I don't think you know, and I don't even know. Regardless, it's who you draft, who you sign to a free-agent contract. I think that kind of tells what you think. Now, you still have got to execute."

Fox added: "We watch these guys practice every day. That's the unique thing we get to evaluate. I've seen steady growth. It's altogether different I think. Most quarterbacks would tell you that. All of a sudden your experiences in college, your experiences in the preseason, and then you get to the regular season. People talk about this as well. You get to a playoff game. It ramps off. So you don't really know that until you put somebody out there. You'd like to have them as ready to take the test as possible, and typically the more you study the better you get."

In injury news, the Bears placed veteran safety Quintin Demps on injured reserve Friday with a fractured forearm.

Demps was signed by the Bears as an unrestricted free agent after he intercepted a career-high six passes for the Houston Texans last season.