Hi Carlos and thanks for the response. If I'm understanding what "rake the face" means, I don't think my son has ever been taught that method but there are as many opinions on this stuff as there are instructors and armchair quarterbacks. Yes the number is important but there is much more to throwing runners out than that. Kevin Schnall with Coastal Carolina preaches that they throw a ton of runners out with a 2.15 because it's timed, accurate, and repeatable. A 1.8 isn't much good if it's not on, or near, the bag or if a pitcher isn't doing the things required to keep the runners close.
I can't say that I know what coaches and scouts think about it one way or the other but guys have success with both methods. Injury doesn't necessarily mean something is wrong with mechanics of course. It's an interesting debate and if you just want to talk catching at some point, since your son is so young, I can give you some insight as to my son's experiences. Just PM me and I'm happy to share what I've learned or answer any questions. I really had no knowledge of catching before my son started playing baseball but he's basically been a "CO" since he was eight years old 
. Take care!