I honestly wouldn't call that "historic"....its a lot of sleet yes, but there has been areas that have received way more. During the February 1-2, 2011 Groundhogs Day Winter Storm, parts of South Central Illinois had reports of anywhere from 4 to 6 inches of sleet if I remember right. Probably some other areas have had as much if not more before, I'm sure. Its definitely a lot of sleet and hard to shovel, but 2.5" is no where near the record.
At the same time, I got 24.5” of snow in Menominee MI. Local papers said it was the second most for us from one storm. The previous snowiest April on record for Green Bay WI was 16”. They have received 36” of snow so far this month. Ugh!
Records and history aside THAT IS A LOT OF SLEET. Here in NE we only see a little icing of sleet before we get pounded with the snow and wind. Frankly I don't recall an accumulating snow event in my life