Nah not just Ronaldo. Marcelo, Carvajal, Modric and Kroos were a key part in most of these CL wins.
People have been talking about Marcelo's defensive side since his emergence on the scene but he's always the best left back in the world but he plays as he's left winger. Football have moved on and fullbacks now are more evaluated on their offensive side more than just setting, cutting the back and throwing it forward aimlessly. If you can't attack, sprint, cross and provide dangerous output as a fullback you'll never make it at modern football.