He is not saying that Mac Jones will be a top ten pick. Just that Lance may not be, and Jones may sneak ahead of him.
In reality Lance isn't you typical top ten QB prospect, he is really a mid to late first round QB prospect in most years. He is being pushed up because there are many QB needy teams. Guys like Lance go to teams with established QBs so he can sit for a few years and learn the system. Top ten QBs are typically considered day 1 starters, Lance starting Day 1 would be a disaster. Mac Jones is typically an early day 2 QB, he is not boom or bust. He will either be a good QB day 1 or an eternal Backup.