There are 227 pitchers with at least 20 IP who have started at least three games this season. The Brewers have 10 on that list, so call it 217 that they could have faced. Assuming that the ESPN list used is the same as Fangraphs (unlikely, but we'll roll with it), the chances of facing one of those top 23 pitchers in any one game is about 10% (10.6% to be precise).
The Brewers have played 112 games so far. Assuming random assignment of any one of those 217 pitchers for any of their 112 games, the expected number of times facing one of those top 23 pitches is 12 whereas they have faced them 15 times.
So, statistically, they have faced top 23 pitchers more times than expected so far this season. This jibes with what I looked at earlier this summer, where the of the first 20 or so games the Brewers played after they started to get "hot", only 3 of them were against SPs with an ERA >4.00.