IMO, Pedro is garnering far more potential energy with his more athletic delivery. Notice his high knee kick compared to Prior? Notice how Prior lands on his heel.. unlike Pedro? To me, all of this points to lost potential energy on the part of Prior.
As for linear vs. sweeping, it's in the eye of the beholder. Both actions have to occur to reach foot plant. But the motion should be steadily more linear as it approaches foot plant, to maintain balance and flow.