Is it the quarterback or the offense? Bears coach Marc Trestman has neither the time nor the ego to take a bow.

‘‘I would never put it on the system,’’ he said. ‘‘I would put it more on the work ethic of the player, his focus on doing his job well. [Josh McCown is] detail-oriented, just like Jay [Cutler] and quarterbacks who are efficient playing the game. Josh is one of those guys.’’

With all due respect for Trestman’s modesty, it’s the system. It’s the players around McCown, too. But mostly it’s the system and coaching that have made McCown the NFL quarterback he always hoped to be.

It’s unlikely McCown’s work ethic or attention to detail was any different than with any other team he’s been on in the NFL, and he never was this good. His career passer rating was 71.2 before he met Trestman. Even when he started 13 games with a young Anquan Boldin and Larry Fitzgerald in Arizona in 2004, it was 74.1. The difference in Chicago is obvious.

‘‘If I could be a quarterback for any coach in professional football, with no hesitation I would take [Trestman] as a coach, along with Matt Cavanaugh,’’ CBS analyst Phil Simms, a former Super Bowl-winning quarterback, said Monday on ‘‘NFL Monday QB’’ on CBS Sports Network. ‘‘And I want to run their offense. It’s so clear, so precise. Jay Cutler was playing exceptionally well. Now we see Josh McCown — he knows what he’s doing on every play. You can tell there’s a calmness about him. Why are they so calm? Because they are prepared and they feel good about what they’re doing going into the game.’’

McCown is not just playing well in Trestman’s offense — he’s maxing out. He’s not dinking-and-dunking. His yards per pass attempt (7.5) and yards per completion (12.4) not only are career highs but are better marks than Cutler’s this season (7.2/11.4).

Cutler still has 16 of the Bears’ 18 pass plays of 30 yards or more. But he also has 12 of their 13 biggest losses on pass plays — most of them sacks — and all eight of the Bears’ interceptions.

McCown is giving the Bears the best of that middle ground. He has played well in a pinch, as a starter, on the road, at home, against a 4-3 defense, against a 3-4 defense, during the day, at night, in prime time, in great weather and in inclement conditions.

His performance against the Baltimore Ravens is the most impressive of all. In swirling winds and on a soggy field, McCown had 10 completions of 12 yards or more and averaged 7.0 yards per attempt. The last time the Bears played in conditions even close to that — against the Houston Texans at Soldier Field last year — Cutler averaged 2.9 yards per attempt, Jason Campbell averaged 4.9 and Matt Schaub averaged 3.7.

The biggest test remaining for McCown is staying power. Even in Trestman’s offense, the line between success and failure is as fine as ever in the NFL. With the Oakland Raiders in 2003, injuries to Rich Gannon and Marques Tuiasosopo forced Trestman to turn to retread veteran Rick Mirer in Week 9. Through three starts, Mirer was rejuvenated — passer ratings of 106.4, 111.9 and 93.3 with no interceptions in 69 pass attempts. He even had to remind everyone that Gannon still was the starter.