The Steelers are fresh after getting an unexpected bye. Before their bye they led the NFL in sacks. They average five sacks a game. Carson Wentz isn't having a good season. He's been sunk by multiple injuries in Philly's offensive line and receiving corps. 
Because of that this is a bad matchup for the Eagles. The Steelers blitz from all angles. The Eagles' offensive line already is down Brandon Brooks and Jason Peters and now Lane Johnson is hurting. 
Ben Roethlisberger has shown he's fine with 7 TD passes in three games and just one interception. A healthy James Conner makes a difference, too, for the Steelers' offense.
Pittsburgh is traditionally strong in October under Mike Tomlin going 20-7-1 ATS.