The cruise lines have to pay additional rights to show games on the big screen. We were in the Med during the World Cup last summer. Princess popped the extra fees to show US & Italy matches (the ship sailed between Venice & Rome.) They also showed the games in the disco, but I don't think they specifically had a sports bar.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014
I was on RCCL last month and the bartender told me that they showed the uperbowl one year in the theater!!!! That's crazy - people must have been disturbing others everytime they got up to use the rest room. And I imagine bar service was super slow.