Martin has been ruled out through injury since the start of February and the Rams' form has taken a slump in his absence.
The Rams have not won any of their last six fixtures and Birtles believes that Martin being on the sidelines in a major reason behind this.
"I just feel that they are missing Chris Martin so much. Not just for his goals, but for his all round ability," he said.
"Martin is not all about goals he scores, he is always available for the midfield man in possession and he brings them into play. That's why midfielders score a lot of goals off him."
Martin's injury may not have been so costly if it wasn't followed by on-loan striker Darren Bent also being ruled out.
Bent had looked set to cover for Martin, but his injury left Steve McClaren's side short of options and they have lacked a goalscoring threat since.
It has seen them slip down to fifth in the Championship table and they now are looking nervously over their shoulders at the play-off chasing pack.
Although Derby should still have enough to hold off the challengers, their bad run is a concern and they need to break out of this slumber soon.
The good news for the Rams is that Bent played in their most recent fixture against Wolverhampton Wanderers, but Martin's return still seems some way off.