Laurie Zimmer was bad

Going to have to disagree with the OP. I thought she played it "cool and professional" - and that was completely appropriate since she was the only experienced cop in the building, and someone had to keep the group together.

She wasn't all impassive steeliness, either. There was some nice chemistry between her and Wilson, and the developing mutual admiration going on between those two characters was communicated almost entirely through looks, not words. It takes a certain level of acting ability to be able to pull that off.

IMHO, she also made a nice contrast to the other female lead, the flakey secretary. In a lot of ways Precinct 13 was more "real" in its depiction of women than what we see in modern action films where all female characters (seemingly) must be 100% sassy, self-assured, and ass-kicking, never scared. Here, we had two very different female characters: one a professional cop (gun-trained and cool under fire) and the other a secretary (understandably out of her depth and scared).

Precinct 13 was a compact low-budget actioner, with a small core cast, set in what is essentially a single location. There's no room in a tight set-up like that for lengthy back-stories, flashbacks to happier times, or character-developing conversation. Considering the limitations of her role, as scripted, I think she did a great job with what she was given: she was steely and professional, but also vulnerable and human.

I thought she did well. She had this ice cool demeanor and attitude, contrasting the madness around her. It was perfect. It's what you call being understated. Most bad actresses would be chewing the scenery in her role ie Maria Bello in the sorry ass remake of this movie.

The people who think Zimmer is bad in the film probably think that Jennifer Lawrence is a good actress.

I am Djour Djilios. Could you spell that please? I don't think so. Try it with a "D".