You cannot manage an April (or March) game the same way you would manage a September game. You just can't. You'd blow out your pen by June. IMO, Cora left Kelly in one batter too long, but even that decision can be defended, being the first game of the season.
Francona said it best, and I'm stealing this from Speier: There were instances when accepting an increased risk of one loss was the right thing to do for the sake of his team’s well-being in the bigger picture.