Dunno about 50% placement with "biglaw", but I think a lot of schools in the T14 are at or near 50% for firms that pay at or near market. (2000-3200/wk depending on geographic area) I'm at a T14 and know lots of people with multiple offers in that range and several who are splitting.
Like I said, law school prestige is a huge factor for 1L hiring. Undergrad prestige can be a big deal at some firms. Grades always matter for biglaw. And based on my experience and my conversations with people the power of "connections," a lot of times, weren't all they were cracked up to be.
Captain's list of five categories is a bit more accurate than craven's ignorant "generally minority students" comment, but I think Captain underestimates the ability of students with good grades and prior work experience to land a high-paying 1L summer job. And if you're not targeting NYC, Boston, DC, Chicago a geographic connection, good grades at an excellent school, work experience, good personality, and knowing what firms want will generally get you something.