Are teams worse because their players strike-out more, or do their players strike-out more because their teams are worse?
Today's players are, for the most part, selfish and stat-obsessed. If they hit in the late innings of a blow-out game, what are most of them trying to do? What's the most common result of that? If they play for a team that's eliminated by July, what do they spend the rest of the season trying to do? Again, what is the most common result?
Might not account for the entire difference, but it surely accounts for some of it.