Actually, the match rate at UM seems A LOT WORSE this year.
If you look more closely at the Match list and add up the total number Matched this year, you get only 173 students matched. UMMSM's graduating class each year is around 200 (about 150 MD and 50 MD/MPH). The exact size fluctuates a bit every year based on the number of people leaving and coming back from gap years, and the number of students who drop about, but it should be around 200. So that about 27 students or 13.5% of the class that's gone unmatched. Perhaps a few of those have decided to pursue non-clinical careers after med school and didn't match for residencies in the first place, but that's still a lot of people in the class this year without residencies. Also, note that 5 of those 173 are partial matches (ie the 2 matched to Medicine prelims, 2 Surgery Prelims, an 1 Transitional) so that means these 5 people only have a spot in a 1-year residency so far (and need to find another residency afterwards).
This is in comparison with the 2018 Match, in which there are 192 Matches listed, which is more in line with what usually happens:
2018 Match Day Results - Miller School of Medicine Admissions
At the end of the day, I wouldn't let a few top name program matches influence your decision to attend UM (or any med school). As long as you are going to a US MD school, the rest depends a lot more on individual performance than the reputation of the school.