"X-factor" is a term that is used in different ways, but for this situation, it will be defined as: An unknown individual who can have a huge impact on his team depending on where his performance goes. Bryant perfectly fits that description.
The Pittsburgh Steelers offense is built on established players such as Ben Roethlisberger, Antonio Brown, Le'Veon Bell, David DeCastro and Maurkice Pouncey. Bryant isn't the only unknown commodity expected to play a significant role, but he is the one with the highest potential impact.
The 23-year-old receiver was a fourth-round pick last season.