The Albion midfielder has gone to Championship outfit Swansea City for the season.
He has generally been considered to be a deep-lying midfield who can buzz about efficiently ahead of the defence.
But there were times in pre-season games in Marbella when he carried the ball forward with menace.
Sheehan says signing him is a coup for Swansea and that he offers various options.
The Swansea boss said: “I think he is a player who can play as a six, eight or 10. I think he can play in the sides as well.
“He is a player who is full of energy and has a wonderful intensity to his play but also he’s technically a very good player.
“To add a player like that to the squad, we are absolutely delighted. We're very excited."
Yalcouye watched Swansea play Crawley in the Carabao Cup on Tuesday and is eligible to face Sheffield United this weekend.
Sheehan added: “He is a player who has got a lot of ability, wonderful energy.
“We want good players here, the right people, and for him to buy into it and be here, it’s a wonderful signing for the season.
“He has got the capabilities [to play in the Premier League].
“We want to evolve him and improve him and integrate him into our surroundings and our culture so he can be an asset for us.
"He has a great utility for us. He's a player that will bring a lot of energy, a lot of quality, and he's a player that we valued very, very highly in the game.
“So, when we had the opportunity to speak to him about coming to the football club, against the clubs that were interested in him.
"It's a wonderful coup to have him for the season."
Yalcouye has spent significant playing time alongside James Milner in the Albion midfield this summer, which will have added to experience he gained in the Austrian Bundesliga and Champions League with Sturm Graz last term.