By Chris Emma—

(CBS) There’s no mistaking the natural abilities of Bears rookie quarterback Mitchell Trubisky, the second overall pick who has looked every bit of his high billing through three preseason games.

Trubisky can make all the throws – a deep ball down the sidelines with precision, the right checkdown to avoid a mistake, a ball to the first-down marker while flushed out of the pocket. He has a tremendous throwing arm and ideal mobility to make plays.

What Trubisky needs are the reps, and that’s exactly why the Bears have decided to start him in the preseason finale against the Browns on Thursday at Soldier Field. Though he’s now the most important player at Halas Hall and this exhibition is the most useless of the four, this is a valuable opportunity for game-like experience.

Trubisky will lead the Bears as the starter, then Connor Shaw will assume quarterback duties later on as starter Mike Glennon and backup Mark Sanchez will join a long list of players not suiting up for the game.

How Trubisky responds to a mix of personnel will be among many things to watch for in the preseason finale.

Who catches on?

To say the Bears have uncertainty at receiver is an understatement. Cam Meredith, who wasn’t even active for the 2016 regular-season opener, was set to enter this season as the Bears’ surest target at receiver until he suffered a torn ACL in last Sunday’s game. Kevin White will now be counted on as the Bears’ top target, but he has just 19 career catches in four games and has undergone two surgeries in two seasons.

The Bears need to identify targets this season, and perhaps Thursday can bring that opportunity. Victor Cruz, Tanner Gentry, Deonte Thompson and Josh Bellamy are among players fighting for a job, with Saturday’s roster cut-down looming.

Cruz and Gentry in particular have something to prove. Cruz is a 30-year-old veteran who has left more to be desired with the Bears, while Gentry is an undrafted rookie who has shined in the preseason. Both could benefit from a strong showing in the preseason finale.

Five spot

The Bears have loaded up with options at defensive end, looking to find the piece to complete their front seven. Thursday will provide an interesting look at the battle for reps at the five-technique.

With Akiem Hicks sure to sit, the Bears will work their depth at defensive end for four quarters. This will bring an important evaluation for Jaye Howard and Roy Robertson-Harris, both of whom have displayed strong form as of late.

Robertson-Harris recorded two sacks in the second preseason game, while Howard is nearing full health and revealing his form after recovering from hip surgery this offseason. Both could earn a key role on the defensive line.

Fuller go

Cornerback Prince Amukamara wasn’t present at practice Tuesday at Halas Hall after suffering an ankle injury Sunday, and while coach John Fox referred to his status as “day-to-day,” one can only wonder if he’ll be ready for the regular-season opener on Sept. 10.

This means Kyle Fuller will have one more opportunity to secure a place with the Bears before Saturday’s cut-down deadline. Fuller has been healthy all preseason, which was the first step for him after missing the entire 2016 season with a knee injury. The Bears were disappointed they didn’t see Fuller “champing at the bit” to return and play last year.

Fuller has made strides to earning his place with the Bears for 2017. He’s even working a role in special teams, which will be a requirement for him to remain on the roster. If Amukamra were to miss time, Fuller would be the next man up.

Chris Emma covers the Bears, Chicago’s sports scene and more for Follow him on Twitter @CEmma670 and like his Facebook page.