It's a worthy area to highlight in my opinion.
The corridor of uncertainty should be a "thread the needle" type of pass for the attacker, one that gets the central defenders, as you say, tracking their man but hoping they don't have to touch the ball for fear of putting it in their own goal and an area that the goalkeeper doesn't feel like they can come into.
With Begovic, this area isn't a thread the needle area as the team bus could drive through it and I think it's an area that more and more clubs will try and use because it's easy to scout.
Barnsley flashed probably half a dozen of these across the box and a better side, like ones we've played this week for example...will score at least one of those chances if not a couple.
Intriguingly Begovic did finally get down to one in the 92nd minute last night. This has confused me entirely. He's failed to come for nearly every single one of these crosses since his last run in the Premier League and so far this season. So you'd think it was just something he prefers to do, like pushing the ball away instead of catching. But the fact that he did actually come for one, now has me wondering what the tactic and thought process behind it is.
Personally, as a team, we need to get better at stopping these crosses at source and Begovic needs to command his six-yard box better. If the ball is being flashed across between the penalty spot and the six-yard box for example, sure that's the defender's job to stick with his man, after all, space can't score, but when it's only three, four, five yards from the goalline, then you want your 'keeper all over that.