I founded a successful PR and social media consultancy in 2002. I have worked with major national brands, both companies and nonprofits, to develop award-winning social media campaigns. I have won awards and been featured on a number of lists (you can check that out here http://ow.ly/APNrz), but mostly I love to connect people with the resources they need to succeed in social media.
Bleacher report is owned by Turner Network and CNN extensively links to them as a source. CNN makes up all of their top linking domains. This helps their online visibility. Couple that with the extreme loyalty of sports fans and it makes sense they have huge engagement.