Okay, so I did my own Googling <is that a word?> and I see what you mean. Being from a state with a long history of these fish, I also checked our DNR website. Here's a link to their report:
http://www.michigan.gov/dnr/0,1607,7-153-10364_18958-45690--,00.html
From my own standpoint, I don't normally figure smelt as a baitfish when I'm think of bass. This is probably because our population lives in the depths of the great lakes for most of the year, and only come into the shallows during the spring of the year to spawn. I have seen maybe twice where strong easterly winds have driven near shore water temps down into the 40's in the fall where they have shown up while I was pier fishing for salmon, but it doesn't happen very often.
We also have a number of inland lakes that have decent populations of smelt where the bass may get the chance to key in on them from time to time. But still as a forage for bass, I don't really consider them a primary source. These fish live in the deepest and coldest water (remember their preferred temp is 45 degrees), and are normally only active at night. So when I look at the difference of habitat between bass and smelt, they just seem too far apart.
I could only think to put the two together would either be in the early spring, or perhaps to the late period after the fall turnover (when water temps from shallow to deep mix equally) just prior to ice up.
One last note is that the little critters are fairly tasty!