The 20-year-old playmaker made his return from injury as a second-half substitute in Saturday's 4-0 defeat to the Blues at Villa Park.
Black was speaking to AVTV following the match at Villa Park, where goals from Ruben Loftus-Cheek, Alexandre Pato and a second-half brace from Pedro condemned the hosts to their seventh straight Premier League defeat.
They now sit 15 points from safety at the foot of the table with only six games remaining and relegation for the first time since 1987 looks all but inevitable.
Unsurprisingly, few players gave a good account of themselves on Saturday lunchtime as the visitors cruised to a convincing win, but Black was quick to praise Grealish for injecting a bit of life into the side following his 66th-minute introduction for Carles Gil.
The 20-year-old midfielder had not played for Villa since twisting his ankle in training in February, just a few weeks after missing three matches while recovering from a bout of tonsillitis.
He has only made four first-team appearances this calendar year as a result, and having also run into trouble for his off-field conduct earlier in the season, the Solihull native has received strong criticism amid the club’s slide towards the Championship.
Nevertheless, he looked refreshingly sharp on his return from injury, completing 92 percent of his 12 passes while recording one shot and creating a chance, and Black gave the fit-again attacker’s 24-minute showing a positive review at the final whistle.
“I was really pleased with his contribution,” Black told AVTV. “He brought something in the last third that we’ve maybe been lacking – that direction, that ability to retain the ball – so I’m pleased to have him back.”
On his side’s overall performance, Black said: “I’m disappointed. We started off the game ok and were in it, but then we concede a goal, concede a penalty, lose a goal after half-time – so all the things that you preach go at the window out that point.
“Then it’s just relying on the reliance of the players to stick to their professionalism and do their job, and obviously at 4-0 it’s an extremely bad day for everybody.”
Black originally joined Villa from Championship side Rotherham United in January to work as a first-team coach under Remi Garde, but the Frenchman’s departure earlier this week means he is now expected to lead the club through their final six games of the season before a new manager is appointed in the summer.
The 52-year-old Scot’s second match in caretaker charge comes next Saturday at home to Bournemouth – one of just three teams the claret and blues have beaten in the top-flight this term.