Myhill has been kept on the sidelines by the performances of Ben Foster but he seized his opportunity with both hands while the former England keeper recovers after a groin operation.
Clarke said: "I'm not surprised with how Boaz has done. I've watched him work in training.
"I've seen a dedicated pro who was working hard so that, when his chance came, he wouldn't let us down.
"I know he was ready for his chance and I'm delighted he has taken it the last two games. He has been terrific.
"But I see that in a number of players in the squad and for me that's the most pleasing thing.
"I can make one or two changes every week and the performance of the team never suffers.
"I've got a squad of players here who are all committed to what we are trying to do and I think you can see that."