No excuses at all for Aoki, because if IU and, especially, Oregon State can have some success, there is no reason that ND cannot, but this is a damn difficult conference now. It is comparable to the SEC and PAC 12 (ranks ahead of the PAC 12 in RPI right now, for that matter) and Big XII. It's definitely the best baseball conference ND has ever been in, and really, that should be a selling point when recruiting against Michigan and IU and virtually every other Midwestern and East Coast program.
An elite program with which I am familiar - Louisville - absolutely feasts off good Midwestern recruits (McDonnell basically sweeps the Midwest for almost all of his good players). This isn't football, and there are a lot of good prospects to be found in Illinois and Indiana and Pennsylvania and Michigan and Ohio; take a look at the origins of Louisville's bevy of draft prospects from the last decade - a few are from Kentucky but most are from the Midwest. Tuition is a problem, but that can be overcome with the right support.