It's very possible that it's lag, especially if those healers are from Europe.
The healer is out of titan's ability and he shows as still charging it up on his/her end, but on the server's end, he/she's still in it, so he/she gets hit by it and thrown to his/her death (or simply takes a ton of damage if he/she doesn't fall down).
The only way for me to manage to dodge Titan's ability was to move before he started casting it on me, just as I thought "here, he's turning around to cast it on me, I'm feeling it!".
Yeah, it's lag. One of our brds had a tough time at first because of lag, eventually you realize his pattern and can start moving a bit in advance.