Wilson shouldn't be your benchmark for QB quality. He is tough, he is a pretty good runner, and he doesn't make a ton of mistakes (except for failing to read LBs on slant passes - he repeats that often). Beyond that, his throwing has really been sub par. I broke down his game from yesterday, and if you eliminated passes that were behind the line of scrimmage, he would have thrown for 30%. That's why his yardage numbers are lower. If he was throwing down the field more often, his percentage would be much lower.
Mangum will be a good one and as far as pure throwing goes, he is already better than Wilson. But there are other factors that go into QB performance and Travis does have some positive qualities.