I think Timmy has come under criticism unfairly in a lot of ways. Its happened with the Yak, people realising his inadequacies when his scoring isn't up to form and Cahill not being the catalyst when we lack a distributor or creative force.
Cahill reads the game well, but his style is a breaking midfielder supporting the front man. When he gets the ball he looks horizontal for a simple pass and gets in the box. This is why he has scored more premiership headers than any other player. His style has never been to run the game or control the flow of the team, we have many players better at it. Recently we haven't had creative players and Cahill has been used in almost every role a midfielder can play.
You can't just heap extra pressure on players and expect them to excel where they haven't been used before. I think a lot of the criticism is derived from Fellaini performing the central distribution role admirably in recent weeks, while previously been the subject of vilification.
Cahill often scores against big teams and when we counter attack, but like the Yak relies on service.