Gladwin was booked for a challenge that took out Charlie Taylor in the first 45 minutes, and two more dangerous challenges were lucky to escape further punishment and a second caution.
But it appears Gladwin was also carrying an ankle knock that prompted his boss to remove him from the fray in the 56th minute and bring on Jordan Cousins for his debut.
"Ben is a boy who gives you 100 per cent," Hasselbaink said.
"He was a little bit unfortunate with the first yellow card. That was a little bit harsh, but he also had a problem with his ankle and I had a decision to make.
"So it was two things, not only the yellow card, but the injury."