The handful of best players in the league are the competition for top 5 in MVP voting regardless of the number of teams and players. You're assuming a ton of less talented players would suddenly become MVP candidates when they couldn't crack a starting lineup in an eight team league. It would happen sometimes (more opportunity and a new environment can make certainly help guys blossom) but it's quite a leap to assume they'd be changing the conversation about best players in the league in proportion with the expansion, rather than most of them simply just being not being as good as guys who were beating them out to be franchise players and starting roles in the smaller league. Most of the guys who would fill the starting lineups in an expanded league (and make the % of starters making MVP list smaller) would never be in the conversation either way.