Ryan said: "Cardiff were extremely impressive and are by far the best team we have faced this season. It's just unlucky for us that we've had to face them three times.
"There's a big gap between where we are and where the Blues are. They have the balance right. They have significant power in their front five as well as the midfield in Tom Shanklin and Jamie Roberts and real cutting edge in the backs in Leigh Halfpenny.
"Right now they are hard to match in Europe. Their work rate is obvious."