If you aren't at a top school (i.e. 1-10) or don't have top 1/3 grades or so, you are going to struggle in OCI. The ratio means nothing. We have over 400 employers up for OCI, however, when you are in a competitive legal market, that doesn't mean the job offers are just going to pop out.
OCI employers aren't required to take any students from a particular school if they don't choose to. They simply agree to participate in OCI.
That makes some sense, but your response somewhat distorts your point. The number of OCI firms means very little depending on the class size. I think the ratio indicates a lot more. 400 firms for a class of 400 is worse than 400 firms for 200 students. Being top 1/3 at the former probably wont yield anything, while top 1/3 at the latter would. From the firms standpoint, it doesnt make much sense ot go out of its way to participate in OCI and not want to firm 1 hire. Even at my old school, I had interviews with 2 of 6 spring recruiters as a 1L. Nothing came of that, but I would think my chances are better at a better school, more firms, and more firms looking to hire my class type (ie, more want to take on 2Ls rather than 1Ls). Way too many spout off how difficult it is, but just the other day, I read a post from a 3L at BC who was wasnt even top 1/3that found solid work through OCI.
Nonetheless, I do agree that at schools 30 (perhaps 35) and lower have difficulty finding success at OCI. I checked my old school's (a low t1) OCI and the least stringent reqt was 1/2, while the majority were 1/4 and up. So I agree that what you say is true for the majority of schools, but good options exist at OCI for students at outside the top 1/4 at non-T14 schools as well.