Oddly enough, Hammer Station seems to be the one which shows the inexperience of players the most. 9/10, it's the last boss, or the first fight (the one with the two large droids) which causes inexperienced (or, experienced but not very good) people to drop the ball.
I remember having a conversation about this several months ago, and the consensus explanation for this is that Hammer Station is such a huge skill jump from the only other Flashpoints lowbie characters might've accessed, Esseles/Black Talon.
I didn't start doing the low level SM FPs until I was starting my second round of characters, and even though I was experienced with the Level 50 HMs, I found Hammer Station to be a crapshoot in terms of getting through it. It's rated level 15-19, but there is such
a power difference between even level 15 and level 16. IIRC, some tanks don't even get their Taunt until level 17.
Combine these, if you get some inexperienced players and/or running at the lower end of the level requirement, and it takes a herculean effort to clear it.