Wednesday's Chris Maguire converted that penalty and Afobe added another in the second period.
"I thought it was the correct decision," Gray said of Pearce's red card.
"Perhaps we had a bit of luck in the first five minutes, when they missed their two chances, but I thought we dominated after that.
"I'm grateful to Arsenal for letting us have Afobe. He's got real talent and caused Reading a lot of problems with his pace and power.
"But it's not really fair to pick out individuals. It was a collective team performance. With a bit better finishing, we could have finished them off earlier."
- Sports & Recreation
- Alex Pearce
- Benik Afobe
- Chris Maguire
- Nigel Adkins