CHICAGO — Many coaches are hired because they are from a prestigious coaching tree, or because they can follow a proven program.

Mike Martz is from the tree of Don Coryell, who could be inducted into the Pro Football Hall of Fame on Saturday.

But that isn’t why the Bears hired him.

Martz is that rare coach who uses the system as a foundation, but is not bound by it. He is as much an artist as a coach, and is more likely than most to attack a given defense in a manner in which nobody suspected.

In many ways, he is the offensive equivalent of Jets coach Rex Ryan. Like Ryan, he is going to take risks, attack, and force the opponent to leave its comfort zone and adjust to his calls.

I have known Martz since his heyday with the Rams and have been fortunate enough to talk with him quite a bit over the years about offensive football and his vision of it.

Assuming Martz will do what he always has done, his offense will be very different from Ron Turner’s. The language will change completely, from words to numbers. There will be more pre-snap motions and shifts. Checks and audibles will be cut back to almost none. The field will be spread much more, and Martz will use more four wide receiver sets — which were almost unheard of with Turner.

As different as Martz’ offense will be from Turner’s, there is a philosophical connection between them. Martz worked for Turner’s older brother Norv in Washington, and both the current and former Bears offensive coordinator have been influenced by Coryell, the former Chargers coach.

Whereas Ron Turner usually plays the notes that are on the sheet music, Martz is more likely to play what he feels. Unlike about 99 percent of the play callers in the NFL, he does not script the first 15 to 20 plays. You won’t be complaining about the lack of halftime adjustments this season. And when his team is in a two-minute drill, he never even looks at a call sheet, he once told me.

“You just go by feel,” he said.

He believes in never running the same play twice in a game — not even from a different formation.

Martz is an instinctive play caller who goes into games with hundreds of play possibilities, and then picks and chooses based on circumstances. And even with all the game plan has to choose from, it isn’t always enough for Martz.

Remember the game-winning 73-yard touchdown bomb from Kurt Warner to Isaac Bruce in the final two minutes of Super Bowl XXXIV? That play wasn’t even in the game plan — but Martz called it anyway.

“You don’t want to say this is what we are, this is what we’re going to do,” Martz said. “You may have to change some things because of what the opponent does, you may want to move in a different mode. But once you settle in on things, we try to be less reactive and just take charge and do it.”

If the Bears under Turner ran to set up the pass, the Bears under Martz will pass to set up the run. The idea is to be more aggressive in the first half and more conservative in the second.

Martz doesn’t go into most games planning on throwing it 60 times. He goes into games planning on doing what is necessary to take a lead and put away an opponent. And if that means throwing it 60 times, so be it.

When I asked him once about criticism for not running enough, he said, “I could care less how many times we run the ball. The whole logic is to win the game. I could care less about balance. When I call a game, it’s based on what’s going on out there and what I see.”

Percentage of runs and passes, as well as time of possession, is inconsequential to Martz. Whereas Turner says the most important measure of the running game is number of runs, Martz says the most important measure is yards per carry. He would rather have Matt Forte run it once for six yards than three times for six.

The most important aspect of a Martz offense? His pass protections. “That’s first and foremost for me,” he said.

When he was with the Rams, Martz once had 37 protections in his playbook. And he wasn’t timid about using them. In one game he showed me on tape, he called five protections on the first five plays.

A Mike Martz offense can be unconventional. It can be unbalanced. But it can’t be uninteresting.