It matters who plays quarterback, and it also matters how you play, no matter who plays quarterback.
That's what we learned in the Detroit Lions' 20-13 loss to the Chicago Bears at Soldier Field. Jeff Driskel started at quarterback in place of Matthew Stafford, who was out with hip and back injuries.
Among the other things we learned: A six-minute lapse in an otherwise solid effort by the defense was costly; no starting quarterback in the NFL can be taken for granted, as was the case with Bears QB Mitchell Trubisky; penalties, big and small add up.
We start with the quarterback change:
Stafford is an elite passer and in his prime, and a drop off would be expected with any backup.
Driskel had a lot working against him. He signed with the Lions after the second game with scant NFL experience on his resume. He started five games for the Bengals at the end of last season. He completed five of eight passes in the second preseason game for the Bengals this year and hadn't seen any kind of live action since then.
It was asking a lot for Driskel to step in and win a road game against a Bears team that has one of the NFL's top defenses. He didn't get support from the ground game, and the Bears' defense put the clamps on the Lions' offense after giving up a field goal on the Lions' first possession and another in the second quarter that gave the Lions a 6-0 lead.
The defense: It was something the Lions had to lean on under the circumstances, and it held the fort until Trubisky's 18-yard TD pass to backup tight end Ben Braunecker with 25 seconds left in the half. The Bears added two more touchdowns on their next two possessions for a 20-6 lead that the Lions could not overcome.
Chicago's three scores came in a span of 5:47. The Bears gained 155 of their 226 yards on those three possessions. After the third TD, the defense held the Bears to 46 yards, two first downs and four three-and-outs on the final five possessions.
The damage was done on those three TD drives, and the offense didn't help by failing to sustain drives and score.
Trubisky: For all the heat he's taken -- and as poorly as he's played most of this season – he's a three-year starting quarterback who's had big moments.
One was against the Lions last season – 355 yards and three TDs in a 31-20 win at Soldier Field. He was injured and did not play in the Bears' win on Thanksgiving Day two weeks later. He had three TD passes in a road win over Washington during the Bears' three-game winning streak earlier in the season.
Nothing can be taken for granted with quarterbacks. They're all in the NFL for a reason. (Confessing that I did not think Trubisky could beat the Lions – again.) But it's not like Trubisky had never played well before.
Penalties: When they happen is as important as how many are called. The Lions had eight penalties for 76 yards.
Some were especially damaging.
An interference call on third and one against cornerback Darius Slay in the third quarter gave the Bears first and goal at the nine. Trubisky passed to running back Tarik Cohen for a touchdown on the next play.
First and 10 for the Lions at the Bears' 44 in the second quarter became second and 30 on full retreat to the Lions' 36 on 10-yard penalties against wide receiver Marvin Jones Jr. and tackle Rick Wagner.
And a highly questionable interference call on wide receiver Kenny Golladay wiped out a catch by running back J.D. McKissic on third and one that would have been a first down at the Bears' 29. The Lions could not convert on fourth and 11.
Bottom line: The Lions are limited on offense, and Stafford has used his talent and experience to work around those limitations. The defense didn't play terrible, but it couldn't stop the Bears when they got on their roll.
And penalties hurt.
We've learned all of it before. Sunday was a refresher course.