Snapped up on loan from West Ham at the beginning of the 2019/20 season, Diangana was sensational for the Baggies as they went on to win automatic promotion that year.
But the 23-year-old has struggled for form ever since making his loan move permanent in £12 million deal in September 2020.
Diangana has played his best football for Albion from the left wing.
But with Bruce currently playing a 3-5-2 formation, he is competing with Karlan Grant, Callum Robinson and Andy Carroll for a place in the front two.
And the boss believes he has the potential to shine in a slightly withdrawn number 10 role – with Bruce seeing similarities between Diangana and Sone Aluko who he managed at Hull.
“We had a lad Aluko who started at Birmingham and I took him to Hull,” the 61-year-old said.
“He started as a wide player and then started playing as a 10. He thrived in that role.
“Grady reminds me of Sone, a little bit. He has got great ability, he gets into little holes, he holds on to it.
“We have seen bits and pieces from him.
“And we’d love to get Diangana back to where he was two years ago when he lit up the Championship.
“This free role may just help him a little bit, I hope so.”
Diangana played in a front two alongside Andy Carroll during Albion’s win over Bournemouth on Wednesday.
The duo are expected to retain their places for today’s game against Stoke.
And Bruce says he’s thoroughly enjoying seeing Carroll play pain free – with the 33-year-old having suffered a number of injury set-backs in his career.
“I’m delighted to see him play well and stay fit,” Bruce said.
“He has been blighted with a horrible ankle and a few niggly injuries in his career.
“But when he is fit and healthy, he is a real handful.
“And he does it in both boxes. How many headers did he win in our box against Bournemouth.
“He’s playing with a determination that fans enjoy watching.
“He plays with his heart and that’s why he’s been a bit of a cult hero wherever he’s played.”
Speaking after the Bournemouth game, Carroll – who is out of contract this summer – confirmed he wants to stay at Albion next season.
And Bruce said talks will soon take place.
“We’ve still got weeks to go – talks are ongoing,” the boss said.
“All those conversations have to be when it’s right.”
The game against Stoke today is Albion’s third in six days.
And Bruce admits, in an ideal world, he’d rotate a few players particularly in midfield.
“It’s our third game in six days so I’m a bit mindful of that,” the boss added. “In an ideal world, I’d have some more options in midfield.
“We ran a million miles the other day, it was the highest figures of the season we ran against Bournemouth.
“It’s going to be difficult to replicate that. In an ideal world I’d like to change two, three, four of them maybe. But I can’t, we haven’t got enough.”