I think Xenok hit it on the head...companies that recruit at core schools still get loads of applications. Talking with some recruiters/alums their companies would get 100-200 resumes (GM type roles). Of those maybe 8 - 12 get closed list interviews. Then out of the 16-24 interviews they conduct on campus, they give out their offers...sometimes none and sometimes they will give out 10 or more. If a company wants to bring in 20 people from half a dozen core schools they could be looking at 1000 applicants for those positions. They have to weed through to find the people who are serious about the company and the job, and are not just using it as a backup for M/B/B.
Companies also have cores, not just because senior managers or the MBA program manager are alums of the school. A lot of it has to do with students from there are a known entity. They know admission at those schools are going to basically ensure them a certain level of candidate and that students will on average graduate with a certain level of skills. Plus they have developed reputations with students that attracts them, I can tell you that different companies have very different reputations. Overall in the real world they may all be seen as impressive companies you would want to work for...but talking with people who interned or alums who work(ed) there you may get a very different image of what its like as an employer. So students do a lot of self selecting, I did not apply to some very impressive companies because I felt I would hate working there. If I was at another school I would be swayed by the image and probably would have applied off campus to them. I would be willing to go to a school i wasnt happy about because it would be great for my career but I think accepting a job I wouldnt be happy with is a completely different thing.
My advice, if you are choosing between different schools...if you want an industry that recruits MBAs (IB, MC, CPG, healthcare) go to the school with the strongest placement in that area and that has the most on campus stuff (providing there is a big difference). If companies recruit MBA's heavily but not at that school its going to be extremely hard to break in. I got 2nd round interviews off campus and then my ding basically was sorry we loved you and think you would be a great fit unfortunately we are only bringing a small intern class on this summer and will only be taking people from our core schools. So if you have half a dozen companies you would love to work for and 1 recruits at school A but 5 recruit at school B...go to school B. However, if you want something that recruits very few people (eg alt. energy) then its not as big of a factor.
After all the honest answer about why you are getting an MBA is because you want to have a great career not to learn some ground breaking material. If you want that go get a phd.
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Kellogg Class of 2010...still active and willing to help. However, I do not do profile reviews, don't offer predictions on chances and am far to busy to review essays, so save the energy of writing me a PM seeking help for these. If I don't respond to a PM that is not one of the previously mentioned trash can destined messages, please don't take it personally I get so many messages I have a hard to responding to most. The more interesting, compelling, or humorous you message the more likely I am to respond.