What year is this? 2012? Pretty sure we are about to go onto the 2016-17 season. 5.25 is acceptable 3rd pairing dman caphit. Now if that is not something Dallas wants, then fine, but Streit is not a salary dump throughout the league. He might be for Dallas, but he certainly would get interest from someone out there imo. 3 teams currently employ 3 D at 5.25 or more per year (so not a lot) but every year people get paid in free agency so I expect this could grow to 6 or 7, which imo is enough to say paying 5.25 to someone to play 2nd pairing isn't that bad.
If Streit cannot get a decent return now then Philly is likely in no rush to move him and create a whole when they want their youth to mature more. They will just hold onto him until the deadline and move him then when the caphit does not matter as much.