By Nick Selbe Pittsburgh fans, you might want to look away. By any measure, the Steelers’ offense has been a mess this year. But one stat in particular illustrates just how lacking in explosiveness Pittsburgh has been through the team’s first eight games. NFL analyst Warren Sharp posted a tweet on Wednesday showing each team’s longest touchdown play of the season. The Bills have the season’s longest touchdown at 98 yards, while 22 teams have scored a touchdown of at least 50 yards so far. The Steelers? Their longest touchdown of the year has been … eight yards. Eight. Yards. That’s 24 feet—288…