I've never blown off what a player or coach says when they don't agree with what I believe...ever. Not while they're currently on the team. I've never treated their words as irrelevant, unless those words contradict their earlier statements.
The "What do you expect them to say?" response has always been lazy in my eyes, and I've said so numerous times...it's essentially just saying "I don't believe you". For me, who really gives a **** if you don't believe them...explain why are they're wrong.
And the thing is, what Terry said matches what numerous different players and coaches over the decades have said--that throwing velocity can indeed be improved. So why should I give the same validity and weight to a fan saying "No it can't"?
I've also ridiculed the infamous fan "eye test" rhetoric numerous times as well. Which ties into this discussion, unfortunately.