At the very least, put an NFL average offensive line in front of Tua and see how he progresses. Herbert is playing great. Good for him. But Tua versus Herbert is not an apples to apples comparison. Tua had the worst offensive line, virtually no running game, etc. Last I looked, the Chargers were 7th rated with their offensive line. These are the points that most national media, that don't do their homework, are missing.
If Tua can't lift his game with improved talent around him, then that's a problem. But I don't think that will be the case.