Add Jason Heyward to the list of players who might not suit up for the Cubs again this season.

The veteran outfielder is still recovering from a concussion suffered earlier this month when he took a knee to the head running the bases at Wrigley Field. Heyward has been out since that Sept. 11 contest and is currently on the IL.

The 32-year-old is feeling better but is not all the way back and the Cubs don’t know if he’ll take the field again in 2021. After Thursday’s off-day, only 10 games remain on the calendar.

Heyward went through some exertion tests Tuesday to determine how his head is healing and the plan was to undergo the same tests again Wednesday.

“I think in his mind, he wants to do everything he can to get back,” David Ross said. “It’s just such a tricky injury. In my mind, talking to him and starting to count down days of trying to get back, the word I’d probably use is ‘doubtful.’ We’re definitely holding out hope. He enjoys playing baseball and wants to be back with the guys.”

Heyward has played 104 games for the Cubs this year, hitting .214 with a .627 OPS and 8 homers in that span. This is his third trip to the IL this season after a hamstring injury in May and a finger issue in August.

Ross dealt with concussions in his playing career, including in his first season with the Cubs in 2015. He took a pair of foul tips to the face mask in July of that summer and landed on the IL as a result.

So Ross can speak from experience about the tricky nature of head injuries and has had multiple conversations with Heyward, trying to provide guidance and help the 5-time Gold Glover in his recovery.

The big thing Ross has tried to stress is patience. A brain injury is not like a hamstring strain or a broken bone – there is not linear timeline for recovery.

“It’s easy to think you’re starting to feel a little bit better and then getting exposed to different environments or exercise,” Ross said. “The day-to-day things that he has to get back to — hitting, being able to do things on the move, all the things that go into our sport.

“It’s a little bit slower process and longer road for each individual concussion that can take different twists and turns. I think the good news is he’s feeling better on a daily basis and that’s what I hang on to.”

The Cubs welcome the St. Louis Cardinals into Wrigley Field this weekend to close out their home slate. They will then embark on a road trip to Pittsburgh and St. Louis to end the season.

Alfonso Rivas saw a lot of the playing time in right field in Heyward’s absence but now he is done for the season with an injury of his own, so Trayce Thompson has started each game against the Twins.