The Londoners host the Dutch outfit at Craven Cottage on Thursday in the opening group stage game and the arrival of Ruiz could be key for Martin Jol's men says Kelly.
"We've got a lot of games coming up and the manager's brought in players that can play in different positions and adapt. Bryan [Ruiz] can play on the wing, up front or off the front man in an attacking midfield position," he told the club's official website.
"The new singings give us more options so that when we need to change things we can. In the games we have [Europa League and Premier League] that is something we're going to have to do to make sure our Premier League form remains strong.
"We'll do our work and preparation on [FC Twente] this week and I'm sure we'll be picking Bryan's [Ruiz] brain for how they'll attack us.
"They're a good side that won the Dutch championship a few years ago and we're expecting it to be a tough game. It's an opportunity for us to get a good foothold in the group stage early on and get a home win."