Herrera believes Falcao has suffered due injuries.
He told the Telegraph: "Falcao is similar to Wayne (Rooney) in his character. He's very, very humble. Last season, before the injury, he was maybe the best striker in the world. He had a very, very bad injury in his knee and he had a very difficult eight months. Now he's getting better. He never misses one training session - the same as Wazza. He's trying to help the team always. He's always in good positions in the box.
"Maybe he's the best header of the ball in the world. We are going to enjoy him, I am sure. I'm very pleased to play with him. He made me lose the Europa League (when Atletico Madrid beat Athletic in the 2012 final)! Now he's my team-mate."