There is a very large implication that Papelbon is invincible when everytime the Red Sox blow a save, Papelbon comes back up.
His K numbers are down, and not just down, we're talking like down by over 3 K/9. That's substaintial. His FIP and xFIP are at career high numbers, his BABIP (.218) is 56 points below his career average (.274), and he's much more HR prone.
Not to mention, hitters are swinging at less pitches out of the zone than they have since 2009, so he's not fooling as many hitters, and the swings they put on pitches in the zone are getting hit more frequently than anytime in his career outside of 2010.
His stuff isn't as good as it used to be, and he's not the same pitcher as he used to be.
Again, not arguing one way or the other, just making sure all the facts are known.