Shackleton is highly rated at Elland Road, but has found chances to impress limited this season and his appearance against Wolves was only his 12th outing in the Premier League so far.
The 21-year-old clocked 66 minutes in midfield at Molineux and Whelan was delighted with what he saw from Shackleton, noting his energy, commitment and aggressive approach.
The former Leeds attacker also feels that Shackleton shows real game in intelligence in the way he covers round, while when he gets on the ball he always looks to play positively.
“Shackleton, fantastic”, Whelan said after the game on BBC Radio Leeds.
“He showed all that energy, that commitment and desire, that aggressive nature in that central midfield role.
“But it’s the way he covers round, it’s the intelligence in his game as well.
“He’s very positive when he gets on the ball.
“He always opens up and is brave to make passes and make angles for other people.
“He gets forward as well at times and just has energy to burn.”
Shackleton came through the youth set-up at Leeds and has now made 62 appearances in a white shirt.
He will be looking to be involved for Leeds again when they take on Southampton at Elland Road on Tuesday evening.