Compare: Meillet's law should most probably be interpreted as polarization of accentual mobility in Slavic, due to which accent in the words with mobile accentuation had to be on the first mora, instead on the first syllable (in places in paradigm with initial accent).
This is the reason in the words belonging to mobile paradigms in Slavic accent shifts from the first syllable to the proclitic, e.g. Russian accusative singular of mobile-paradigm gólovu, but ná golovu 'on the head', Serbo-Croatian glȃvu, but nȁ glāvu.
Meillet's law appears to not have taken effect in the infinitive of verbs.
In Slavic, these infinitives retained their acute accentuation, thus creating *gry̋zti next to the present *gryzèšь.
[1] Such verbs appear synchronically to be a mixture of accent paradigms a and c.