Harrison has tipped Academy starlet Brown for big things at The Hawthorns after he made his Barclays Premier League debut last term at the age of 16.
And he says 19-year-old striker Berahino is another one to watch out for as he looks to bounce back from an injury-hit season.
"Izzy made his debut and is a player with lots of potential," he told the WBA website.
"If he continues to evolve and has the hunger, drive and determination, there is no reason he can't become an outstanding West Bromwich Albion player.
"But there is lots of work for him to do.
"Saido had a good loan spell at Peterborough but then got injured.
"Had he not been injured he might have had a couple of first-team opportunities before the end of last season."