I think the pitchers are babies/weaker argument is a bit overblown.
First, there are a ton more pitchers in use in MLB than there were "back in the day". Really the number of guys whose arms can stand up to that kind of abuse probably isn't able to keep up with the demand for said arms.
Second, I'd guess (not having checked the stats) that the average pitcher has a longer career today than he did 40 years ago.
Third, I think some of this issue is perception. I mean we remember all these long lived great pitchers from days of yore because they were great long lived pitchers. You aren't going to remember the hundreds/thousands of guys who were 1-5 season MLB pitchers who blew out an elbow or ended up simply sucking their way out of the league. Thus our perception of how macho/strong/powerful the pitchers back then were because we only know/remember the guys who lasted a long time and pitched well. For every Walter Johnson there are 500 nameless wannabes none of us can name.
I won't comment on Sale because I cannot speak with any authority on the issue. However I will ask this question: Some people have compared him to Randy Johnson's throwing motion. I don't know whether Johnson had a classic inverted W or not, but how true is this analogy and how much of a difference does it make?
Riding shotgun on the Sox bandwagon since before there was an Internet...