Here, for your consideration, are the career major league numbers for two relief pitchers:
Though each has a small sample size, there's certainly not much in common between the two at first glance.
If you haven't already guessed, Pitcher A is Jairo Garcia, and Pitcher B is Santiago Casilla -- the same person.
So what's changed? After watching his 11th inning against the Astros, where he threw eight of his ten pitches for strikes in a 1-2-3 inning, I think I have a theory. Casilla is simply trusting his stuff, and pounding the strike zone more. Here are his strike-to-ball ratios for his career:
That's a pretty clear trend. Before revealing his true name and age, Jairo Garcia had a 82-to-102 strike to ball ratio with an ugly 9.82 ERA. After the name change, Santiago Casilla has yet to give up a run.
Perhaps Jay Marshall (5.56 ERA, 9:8 K:BB in 22.2 IP) should consider changing his name...