Lay off of Zach!
Oh, c'mon, stop ribbing Zach. He's a good guy, his heart's in the right place.
I've heard JMS didn't fill in much backstory for Zach, so Conaway came up with some stuff on his own. The story, as I recall, was pretty similar to Garibaldi's -- lots of previous problems, B5 was one of his last chances. Which seems to fit with one of the show's themes, the little guys and washouts making good (Vir, for example). So if Zach has that kind of a past, he probably would have seen someone from it. In other words an experience very similar to Lochley's, and therefore repetitive. Not bad, not boring, just already done.
And trust me, if Zach knew about part of the station disappearing, he'd be working on it! He's learned responsibility.