A member of the NFLPA blasted the league after a medical cart appeared to malfunction moments after Steelers quarterback Mason Rudolph was knocked out of Sunday’s game in Pittsburgh with a concussion.

“Embarrassing,” tweeted George Atallah, the NFLPA’s assistant executive director of external affairs. “I guess $15 billion (estimated league revenue in 2018) a year can’t buy you a working medical cart.”

The NFL is investigating the incident, which reportedly was an “operator error,” according to the Pittsburgh Post-Gazette.

The 24-year-old Rudolph laid on the ground motionless surrounded by teammates after being hit by Ravens safety Earl Thomas during Baltimore’s 26-23 overtime win.

The cart and stretcher were brought onto the field, and a group of six people were seen pushing the cart.

Rudolph eventually stood up minutes later, and walked off the field with assistance. He was later taken to the hospital. The Post-Gazette reported Rudolph indicated he wanted to walk off the field.

The NFL later released a statement, which said the “medical staff determined a cart was not necessary in this instance,” and, “had one been needed, there was a backup cart on the othjer sideline which was immediately available.”

Thomas was flagged for roughing the passer on the play.

Rudolph was named starter after Ben Roethlisberger (elbow) was ruled out for the season. Rudolph went 13 of 20 for 131 yards and a touchdown against the Ravens.

The NFLPA and league are currently in talks over the next collective bargaining agreement.