Brobbey struck acrobatically for Sunderland's second goal to earn a point for the hosts.
“We felt that Brian (Brobbey) had improved a lot,” he said.
“He needed time to change from another club, a new league, a new country and new teammates. He has worked hard and he deserved this reward. Our four substitutes were really important.
“This league is really demanding but also our game model is also really demanding.
“Our players don’t just stay wide and wait for the next pass - they work hard with the squad, otherwise you can’t defend against a strong side like Arsenal.
“They worked well for 60 minutes and then we introduced four new players onto the pitch, and those finishers helped to maintain the energy and the quality of the organisation.”
He continued: “They all have different profiles as well.
“When you start the game with Wilson (Isidor) up front, you know that he will be a threat in behind even though he has the ability to hold the ball up. With Brian (Brobbey) you have a totally different profile, but he is a good goalscorer as well.”