I'd say like 10-15%.
He's very inexperienced and coming off a year layoff. That is rough for experienced fighters coming in against a middle of the road/possible contenders, much less someone who has his lack of experience going against the long time MW champion.
If this fight took place 2 years from now with him having more fights under his belt and not coming off such a long layoff, it would be much closer, maybe even in the advantageous range.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin