The Chicago Blackhawks have been the most successful professional sports team in Chicago this past decade, winning three Stanley Cups in six years since 2010 and making the playoffs every year since 2009. While the Blackhawks (under previous owner William "Dollar Bill" Wirtz), were last in the standings and attendance in the mid-2000s, son Rockwell Wirtz took over after his death in 2007 and rebuilt the organization into a successful hockey dynasty.
The dominance reached its peak in 2013 with their 2nd of three Cups and top TV ratings. According to Crain's Chicago Business,their 2013 local TV rating was a 5.38.
2013 ratings peak
The 2013 season was very historic. With a shortened 48-game season due to a lockout in the fall, the Blackhawks began that season with 30 consecutive games in which they got at least one point in the NHL standings (24-0-6). With the missing of hockey in the first few months and the historic streak, it makes sense that viewership was at an all-time high. They went on to win the Stanley Cup in an historic Game 6 victory over the Boston Bruins -- scoring two goals in 17 seconds -- which was the cherry on top of the most exciting season in Blackhawks history.
Ratings fall
The next two seasons (2013-2014 and 2014-2015) the Blackhawks lost in the Western Conference Finals to the LA Kings in seven games and then won their third Cup since 2010 against the Tampa Bay Lightning in 2015. Those successful seasons saw ratings of 4.29 and 4.30 -- still good for hockey but still a decline. After 2015, the Blackhawks made the playoffs in 2015-2016, and, this season, they recorded the most points in the Western Conference. Still, both seasons ended in early disappointment. This season posted a 3.33 rating, which is significantly less than 2013's peak.
Why the drop?
There are a number of reasons why the ratings have taken a dip. As previously mentioned, the 2013 season was of historical significance and people did not want to miss it.
Not to mention, 2013 was a year where none of the other major sports teams in Chicago were really any good, which made people want to watch them even more. As time went on, it was obvious to fans that while the regular season can be fun to watch, the playoffs are really what matters and that could have factored in to the drop.
While hockey is very popular again with the resurgence of the Blackhawks, hockey is still not as popular as the other sports in Chicago. The Chicago Cubs winning it all last year certainly ate into the Blackhawks' viewership. The Cubs are one of Chicago's biggest franchises and one of the biggest franchises in sports, and witnessing them making history was much more important to many than early regular season hockey games.
Lastly, there just may be a "honeymoon" effect as well. The team was flying high when they were setting franchise records and it was exciting because it was new. While fans want their team to always be good, after a while the excitement level is not the same. It is no longer new, and in a market where hockey is behind the other major sports, it can be difficult to keep the interest level among sports fans consistent.
Future ratings
It is very hard to predict this kind of thing, but the current outcome does not seem very promising. With that being said, the team could certainly make another historic run like in 2013 and ratings would likely rise again. Ultimately, though, only time will tell.