The Steelers opened their season on the road against the defending Super Bowl Champion Patriots.  After a scoreless first quarter, the Patriots scored first in the second quarter when Tom Brady found Rob Gronkowski on 2 consecutive touchdown passes:  from 16 and 6 yards out for leads of 7-0 and 14-0.  The Steelers got on the board before halftime when Josh Scobee kicked a 44-yard field goal for a 14-3 game.  In the third quarter, Brady found Scott Chandler on a 1-yard touchdown pass for a 21-3 lead.  The Steelers responded with Will Johnson's 1-yard run for a touchdown and a 2-point conversion tacked on for a 21-11 game.  In the fourth quarter, the Steelers scored again as Scobee kicked a 24-yard field goal.  Brady and Gronkowski hooked up again on a 1-yard pass for a 28-14 lead.  Getting the ball back with seconds left, Ben Roethlisberger found Antonio Brown on an 11-yard touchdown pass for a final score of 28-21. With the loss, the Steelers started their season 0-1.  It also dropped the team to 2-1 in Kickoff Games.
How many points did were the Steelers trailing by at halftime?
11