This isn't about letting Josh McCown leave, but rather not replacing him with another experienced player.
Tampa Bay was willing and able to offer McCown more than the Bears both in terms of playing time and money. It's hard to blame him for leaving, just as it's hard to blame the Bears for letting him go.
He had by far the most success of his career last year. It may have been unsustainable, but he deserves credit. A good contract and a chance to start are things he certainly earned.
As of now, the Bears have only Jordan Palmer and Jerrod Johnson behind starter Jay Cutler. Considering Cutler has managed a full 16 games just once since he arrived in Chicago, there is a good chance his backup will see the field.
Palmer was fine in the Bears fourth preseason game last season, but he wasn't exceptional and it wasn't much of a real test. He's never seen significant action in the NFL and was well off the radar before the Bears signed him and later brought him back after Cutler was injured.
While the thought that head coach Marc Trestman is a "quarterback whisperer" is nice, it also ignores the fact that he had talent with which to work. McCown was a third-round pick, who would've likely gone higher had he played at a larger college.
Former New York Jets starter and first-round pick Mark Sanchez would've been a good project for Trestman. While many may remember the butt fumble, there is a lot to like about Sanchez.
He has started two AFC Championship Games, thrown over 25 touchdown passes once in a season and over 3,000 yards twice. He did that despite playing with inferior talent and coaching in New York. All Bears fans have seen what a difference coaching and a supporting cast can make.
There are other options still available. Brady Quinn has continued to bounce around the NFL; Kevin Kolb had success in a West Coast offense in Philadelphia, and Matt Flynn doesn't seem to be getting much attention despite doing a good job in Green Bay once again this season.
Another interesting name is Josh Freeman. If he's willing to work to tap into his talent, Trestman can revive his career.
The Bears seem content to go into the season with just Palmer and Johnson. Unless they know something nobody else seems to—as they did with McCown—it could be a big mistake.