Honestly, I don't think Bushrod has played at a "high level." If you go back and review the Lions tape, Bushrod is beaten frequently in pass protection. Brees does a marvelous job of moving in the pocket to avoid sacks in that game. If not for his mobility, he would have been sacked--by my count--at least three times by Bushrod's man. Of course, in the Eagles game (I haven't looked a replay), Bushrod gave up a sack early in the first quarter. The Saints then gave him help (a TE or RB) for the rest of the day.
IMO, if Jammal Brown is healthy, Bushrod easily goes back to the bench.
All of that being said, I think Bushrod has played decently since being placed into the lineup. This is great experience for him, and he should be even better by week 8.