INDIANAPOLIS – There are a few certainties as the Indianapolis Colts hope to build on Sunday’s victory over the Houston Texans with another over the Baltimore Ravens.

• Rookie quarterback Anthony Richardson and Pro Bowl center Ryan Kelly are in the NFL’s concussion protocol after self-reporting symptoms in the second quarter of the win over the Texans.
• Each must maneuver a thorough five-step process and gain clearance from the team’s medical staff and an independent neurologist before stepping on the field against the Ravens.

That about does it for the certainties.

Unlike so many injuries sustained in the NFL’s physically exacting environment, there’s no universally accepted time frame for a return from trauma to the brain. It might be two or three weeks for a sprained ankle or knee, or a player might be week-to-week with a hamstring or toe injury.

Concussions? They can be as unique as stars in the night sky.

That’s why Shane Steichen was noncommittal – more than a few times – Monday afternoon when pressed about the status of Richardson, and Kelly, for this week’s practice and Sunday’s trip to Baltimore.

• Question: How much practice could Richardson miss and still start against the Ravens?
• Steichen: “That’s a good question. We’re going to work through those things and we’ll talk through those tonight. I don’t have a definitive answer for you right now, but we’ll work through those things tonight.”
• Question: If Richardson clears protocol, will he definitely start or would you be extra cautious?
• Steichen: “Like I said, we’ll work through those things. I don’t have a definitive answer on that one for you yet.”
• Question: How do you treat Gardner Minshew if Richardson remains in protocol Tuesday or Wednesday? Does Minshew get all the practice reps?
• Steichen: “We’ve got to do a good job. Again, we’ll talk through that stuff tonight from a game-plan perspective and go from there and then we’ll make that decision as the week goes on.”

The ambiguity clearly serves the Colts well from a competitive standpoint. The Ravens must prepare for contrasting quarterbacks.

“Yes, the problem is going to be the reps,” Baltimore coach John Harbaugh said Monday. “Both do a lot of the same things in the system, and coach Steichen brought the system from Philly and we understand that system. We’ve had a lot of that system in our system, as well, over the years.

“But different quarterbacks, for sure. Richardson has been, man, he’s been tough to defend the last couple weeks. And Minshew, you know how he is. He can get hot and he’s a very dynamic player.

“But they’re just a little bit different in what plays they run specifically. So, we’ll just have to get a feel for that as the week goes on, and really, we’ll have to prepare for both.”

Again, this isn’t gamesmanship from Steichen.

As of Monday afternoon, he simply doesn’t know whether Richardson will make the necessary steps to practice later this week and be under center against the Ravens, or Minshew will make his 25th career start.

The prudent approach will be to give Minshew the reps with the starting unit until the team has a better idea on Richardson’s progress and possible availability. There’s every likelihood Steichen and the Colts won’t know for certain until Saturday if Richardson and Kelly are given the medical OK to play.

Often, the practice routine for a player in concussion protocol is to not practice Wednesday, wear a red non-contact jersey and be limited Thursday – quarterbacks already wear a red jersey – and be a full participant Friday. Finally, he must gain medical clearance.

Maybe one is cleared. Maybe both. Maybe neither.

Recent history doesn’t offer much optimism, but again, every player responds differently when suffering brain trauma.

From 2016-2022, the Colts had – by our count – 34 players on the injury report with a concussion from a previous game. Only seven didn’t miss a game, but that’s deceiving.

Just two played the following game on a regular seven-day turnaround: cornerback Xavier Rhodes in 2021 and guard Quenton Nelson in 2019.

Circumstances might have aided five others in playing the ensuing game. Cornerback Tony Brown (2022), linebacker Anthony Walker (2018) and running back Marlon Mack (2018) suffered concussions in a Thursday night game and had 10 days to recover. In 2017, Cornerback Kenny Moore II and quarterback Jacoby Brissett sustained concussions in a week 10 loss at Pittsburgh and benefited from the Colts’ bye in week 11; each played week 12 against Tennessee.

Eight Colts were diagnosed with concussions in 2022 and seven – Brown was the exception – missed at least one game.

Six have suffered brain trauma since the start of training camp in late July: Richardson, Kelly, tight end Drew Ogletree, linebackers Shaquille Leonard, E.J. Speed and Segun Olubi.

The last time the Colts had their quarterback miss a game with a concussion was in 2016: Andrew Luck. He suffered a brain injury against the Titans and was unable to pass through concussion protocol in a short week. The Colts hosted Pittsburgh the following Thursday night with Scott Tolzien under center.

It’s worth noting this isn’t Kelly’s first concussion. In 2017, he sustained one in week 12 game against the Titans and would miss the final five games, the last three after being placed on the injured reserve list.

 Did we mention the uncertainty of concussions?

Ogletree suffered brain trauma in the season opener against Jacksonville. He was cleared to play against the Texans but was a “healthy scratch.’’

“He cleared,” Steichen said. “Just kept him out.”

Leonard has suffered three concussions, including one during the Colts’ Aug. 17 joint training camp practice with the Chicago Bears and another in week 2 of 2019 that forced him to miss three games.

Safety Julian Blackmon has appeared in 37 games with 33 starts in four seasons. He’s yet to suffer a concussion.

“No, no, knock on wood,” he said. “Injuries are interesting in the NFL. You’ve got a lot of guys who are strong (and) are the top athletes in the world. Freaky accidents do happen.

“I don’t know, I’ve never had (a concussion), so I’ll let you know if that happens to me. Knock on wood.”

The five steps involved with the NFL’s concussion protocol:

• Phase 1: Symptom-limited activity. Rest is prescribed to avoid aggravating symptoms. Light aerobic exercise is allowed, and the player may attend meetings.
• Phase 2: Aerobic exercise: At least 20 minutes of running on a treadmill or riding a stationary bike while under the supervision of a trainer.
• Phase 3: Football-specific exercise. Non-contract drills are allowed, such as strength training and cone drills.
• Phase 4: Non-contact training drills: Participation is allowed in all non-contact drills, including position-specific activities such as throwing and catching. The player continues balance training along with cardiovascular and strength work.
• Phase 5: Full football activity and clearance: No restrictions. The player must be cleared not only by the team’s medical staff, but an independent neurological consultant, which every team must have.

In February, a study by the NFL revealed concussions rose from 126 in 2021 to 149 in 2022. That’s an 18% increase.

At the time, league chief medical officer Dr. Allen Sills attributed the rise to several factors, including an enhanced protocol that “broadened and strengthened” the definition of a concussion. That was sparked by injuries suffered by Miami quarterback Tua Tagovailoa.

Was Richardson’s concussion avoidable?

Steichen was uncertain whether Richardson could have avoided the hit that resulted in his concussion. The rookie quarterback slowed up a tad as he neared the goal line on a 15-yard touchdown in the first quarter. That allowed Houston safety M.J. Stewart to close on him and deliver a big hit that sent Richardson to the ground and his helmet bouncing off the turf.

“Yeah, it’s hard to say,” Steichen said. “I’ll let him [explain], when he gets a chance to tell you guys.

“When he hit the corner, he was like, ‘Oh, I’m scoring,’ and all the sudden the safety came out of there, and then [Richardson] caught him in his vision. That was more of what it was than anything.”

A Taylor (non)update

Steichen didn’t deviate from his previous comments regarding Jonathan Taylor. The disgruntled running back has missed the first of two games while on the reserve-physically unable-to-perform list (PUP).

Taylor was not in Houston with his teammates, just as he wasn’t on the Lucas Oil Stadium sidelines for the opener against Jacksonville. He’s rehabbing an injury to his right ankle and posted a five-second video last week that showed a snippet of his routine.

“Just in regards to Jonathan going forward, he’s on PUP, like we mentioned for the next two weeks, and we’re looking forward to getting him back,” Steichen said.

You can follow Mike Chappell on X, formerly known as Twitter, at @mchappell51.