EDEN PRAIRIE, MInn. -- Sam Bradford might be back against Tampa Bay. He might not. At the moment, there’s not a lot of clarity regarding the injury/return timetable for the Minnesota Vikings' starting quarterback, who missed Week 2 with a knee injury.

In any event, Mike Zimmer feels good if Case Keenum has to start again in Week 3. He doesn’t anticipate the Vikings will sign another quarterback, so the focus turns to improving communication between the offensive line and Keenum, figuring out why there were times Minnesota was late off the ball and remedying protections.

Keenum faced substantial pressure against Pittsburgh’s fast, physical defensive scheme, which limited him to 2-of-8 passing for 39 yards when pressured. He was better when he had time to formulate his throws, completing 18 of 29 passes for 128 yards when not under pressure, according to ESPN Stats and Info.

Pittsburgh brought the blitz on six of Keenum’s 39 dropbacks, which was its third-lowest blitz rate over the last two seasons. The Steelers blitzed Cleveland and DeShone Kizer twice as frequently in Week 1 (30 percent) and utilized the blitz 29 percent of the time in 2016.

As an aside, Zimmer estimated the Steelers brought some kind of blitz at least 24 times during the game. That could be referring to a standard four-man rush where a linebacker takes the place of a defensive lineman. (ESPN Stats and Info counts a blitz as five or more rushers coming in to disrupt the quarterback’s pass.)

Keenum’s two completions under pressure each gained 15 or more yards, but as a whole, if he didn’t have time to throw, he struggled.

So the problem here mainly lies in protection issues, right?

Maybe. But it’s more than that.

“I know we keep saying it’s protection issues, but I didn’t see a lot of protection issues,” Zimmer said. “Sometimes if you got everybody out and about and they bring an extra guy and the line is sliding one way, they’re going to have a free runner and the guy has to come back in and to take the most dangerous guy; sometimes that happens. Sometimes we’re protecting at a certain depth and the quarterback is too deep. Did we get beat sometimes? Yes, but I wouldn’t necessarily call it protection issues.”

There’s always an adjustment for an offense when the starting quarterback is replaced with a backup. A lot of that has to do with how comfortable an offensive line is with the quarterback’s cadence.

“The protecting and the quarterback depth, a lot of these things go hand-in-hand,” Zimmer said. “He got deep [in his dropback] a couple times, and we’re not protecting at that depth. Some of it was that, we were late out of the snap one time. For the most part, we got on the right guys.”

Keenum was only kept clean on roughly 54 percent of his dropbacks. He was sacked twice for a loss of 21 yards, something for which he shoulders the blame.

“Sometimes my feet were not as good in the pocket as they should have been,” Keenum said postgame. “I think some of the sacks were because of me being out of the pocket and not where I need to be in the pocket.”

So it goes both ways. While the offensive line has to do a better job protecting Keenum against defenses, Keenum needs to watch where he’s dropping back and how long he’s holding onto the ball.

Keenum averaged 2.59 seconds from snap to release on Sunday. In Week 1, it took Bradford 2.36 seconds to get the ball out on his releases.

The responsibility is certainly greater for the Vikings' offensive line, and Minnesota will need its run game to find the rhythm it finally showed in the second half Sunday earlier in games.

Tampa Bay pressured Chicago quarterback Mike Glennon on 17 percent of his dropbacks and blitzed the Bears 28 percent of the time in Week 2. If Keenum plays, there’s a chance the pressure he’ll face will feel similar to how it did in Pittsburgh.

Handling that pressure is not a one-unit job. For Keenum to be successful, the responsibility isn’t just on the offensive line. It’s on him, too.