Preseason opener notes: Mike Glennon’s Bears debut vs. Jay Cutler’s

It’s finally here — the moment of truth.

Yeah, right.

The anticipation that fuels the excitement of the Bears’ preseason opener is based mostly in curiosity and the fact that after two weeks of monotonous practices, it’s real football.

More than likely, this will not be much of a “preview.” In 2012, when John Fox brought the Broncos to Soldier Field for the preseason opener, Peyton Manning was picked off by Major Wright and had a 36.3 passer rating. He ended up throwing for 4,659 yards, 37 touchdowns and had a 105.8 passer rating in the regular season.

Quarterback Mike Glennon will start Thursday. (AP)

Mike Glennon is not Peyton Manning. We don’t even know if he’s the Mike Glennon the Bears paid for. But it’s almost needless to say — though not totally needless or I wouldn’t be saying it — that this game will not be a referendum on Glennon, who will make his first start as the Bears’ quarterback-of-the-now Thursday night against the Broncos at Soldier Field.

In Jay Cutler’s Bears debut in 2009 against the Bills, he was 5-of-10 for 64 yards and an interception for a 30.8 passer rating — his regular-season rating was more than double that (76.8). The pick came on a pass to Devin Hester that sparked an over-reaction to Cutler’s very sensible and accurate explanation (“Devin is more of a go-get-it guy. He’s not really a back-shoulder, go-up-and-get-it [guy]. You learn from it.”) that forced Cutler to clear the air. Four weeks later, Brian Urlacher was lost for the season and the Cutler era was off to a roaring start. So if Mike Glennon can just avoid a firestorm, he’s ahead of the game.

Here’s the standard Glennon and the first-team offense is up against: In seven preseason openers with Cutler at quarterback (he did not play vs. Manning and the Broncos in 2012), the first-team offense produced one touchdown, three field goals, 16 points, 17 first downs and averaged 4.1 yards per play in 16 drives.

The lone touchdown was a 10-yard pass to Zach Miller that capped a 13-play, 69-yard drive against the Eagles in 2014. Cutler finished with 28 touchdowns, 18 interceptions, was sacked 38 times and had an 88.6 passer rating — 17th in the league. Miller, who caught another touchdown pass in that game — from Jordan Palmer, suffered a foot injury the following week and was out for the season. You just never know.

So with that in mind, here are three things to watch tonight when the Bears play the Broncos in their preseason opener: 

  1. The starting offensive line. Guard Kyle Long has been easing his way back into the lineup while recovering from a severely broken ankle and doesn’t figure to play. With back-up guard/center Eric Kush out for the season with a torn hamstring, the Bears experimented with center Cody Whitehair at guard and Hroniss Grasu at center — a nod to the possibility that Long might not be ready.

2. Mitch Trubisky. The second overall pick in the draft figures to play in the third quarter — usually a tough situation to draw conclusions from because he’s playing with third-team players (an excuse if he’s bad) and against third-team players (an excuse if he’s good). It’s a tough spot for a springboard — Dak Prescott parlayed first-team reps in his preseason opener (Tony Romo was rested, back-up Kellen Moore was injured) into the starting job with the Cowboys last season; Russell Wilson was the No. 2 quarterback for the Seahawks when he leap-frogged Matt Flynn in 2012.

Trubisky has impressive skills but doesn’t look ready to compete for the starting job — not even against Glennon. But if he has the “it” factor the Bears think he does, he might respond positively when the lights are on. For what it’s worth, Trubisky was an immediate hit as a first-time starter at North Carolina last season — throwing 13 touchdowns and no interceptions in his first five games.

Trubisky is not in the running to start this season. But if he’s good, he’ll likely earn better reps to wrest the No. 2 job from Mark Sanchez.

3. The rookies. Even with Trubisky cemented as a back-up, the Bears’ draft class has been impressive in training camp — particularly tight end Adam Shaheen (second round), running back Tarik Cohen (fourth round) and safety Eddie Jackson (fifth round). Wide receiver Tanner Gentry has been the most impressive of the rookie free agents. Jackson is currently listed as a fourth-team safety, but he figures to get a good shot here. In fact, they all should. The Bears surely want to know exactly what they’ve got. They’re not alone.

Follow me on Twitter @MarkPotash

Email: mpotash@suntimes.com