Your thesis is armour to protect your ideas. Well-conceived, long-considered and oft-checked.
But it’s still just paper. Flaws can make it on to the page. It’ll be good, but it won’t be perfect. There’ll be nothing terribly wrong probably, but your research needs something else to protect it in the viva. Your thesis needs someone to help it shine.
A champion. Skilled, trained, clever, capable, someone who can make ideas move.
Sound like anyone you know?