NFL Network's Mike Garafolo added that the soreness is not a recurrence of the elbow issue that bugged Foles last season, nor is it considered anything serious at this point, per sources informed of the QB's condition.
With Carson Wentz progressing toward a Week 1 return, Foles reworked his contract in Philadelphia this offseason to provide insurance in case of a setback to Wentz.
The Eagles are likely taking a cautious approach with their insurance policy, not needing to push Foles early in the preseason. As the veteran showed with his play down the stretch during the Super Bowl run, Foles doesn't need much prep in Doug Pederson's offense if he's needed to open the season under center.
With Wentz likely to sit out most, if not all, of the preseason, if Foles is held out of Thursday's home preseason opener against the Pittsburgh Steelers, third-stringer Nate Sudfeld would get the bulk of the signal-caller reps. The Eagles also have quarterback Joe Callahan on the training camp roster.