I wroted about Pro-Nation the other month or so.
This one: Supination Versus Pronation (Sept 3. 2015)
I wrote that mainly based on things I've read Mike Marshall write about as well as some other things. Mike Marshall has a free online book on his website where he writes about himself being his own test subject in the field of kinesiology over his baseball career.
My rule with strange unconventional data on the internet is ... first figure out if this person is saying whacky things in order to make money and if that's the case then be skeptical ... in this case his book on his website is totally free and incredibly interesting ... he wants people to read it and he doesn't want any money for this information. He just really wants people to know about Pronation, that's all.
Mike Marshall's free online book: http://www.drmikemarshall.com/FreeCoachingBaseballPitchersBook.html
When you read free data on the internet by interesting fellows, you may come away from it with a case of "View Point Shock" as Ivan Stang refers to the condition in his book "High Weirdness by Mail."
With Mike Marshall's Pronation book I think I did walk away with a bit of View Point Shock and the whole concept of pronation may have taken on some sort of ancient guru-like mythical proportions to it.
Like a hippie who learns about the Cosmos ... and walks away from it all like "whoaaa man, it's like, whooaaa man" ... I think I walked away from Marshall's book all like "whhooooa man, like Pronation, man! Like Whoaaa."
I still think it's a great book though. Don't get me wrong. There's just one thing I want to alter in that article I wrote. There was one factor that I totally didn't think of before making one of the thesis in it. I claimed that Japanese pitchers in the Nippon League's use of pronation style pitches more frequently (i.e. the Shuuto) was a factor in why Japanese pitchers required less surgery and were healthier during their careers.
There is a more obvious factor though that I failed to consider (as such).
Other Factor in Why Japanese Pitchers are Injured Less Often than the Ones in MLB
The screwball is still a great pitch and is proven by Marshall that the myth that it "destroys arms" is unfounded. He has adequately proven Supination does far more damage to arms than pitches that require Pronation to achieve their breaks. He has indeed proven that the screwball is no more dangerous than any other pitch.
It is no more dangerous ... but is it safer than other breaking balls? Possibly, yes. Yet, the claim that I made that it was highly probable that Japanese League Pitchers are not injured with the same frequency as MLB pitchers due to their use of more pronation break pitches, may not be fully correct. There's a great big factor that was not considered on my part.
The factor that was not considered was that Nippon League pitchers have a lot more rest time than Major League Pitchers. The Japan league over there starts in mid March and ends in early October, a bit longer than the MLB calendar. BUT, They only play 146 games as opposed to 162 games.
So, they take the same amount of time to finish one season but they play 16 less games. I was looking at the Yomiuri Giants schedule for 2016 and there's large chunks in some months where they have 5-7 days off in a row. You wouldn't find that in an MLB team's schedule.
Example month: http://www.giants.jp/en/schedule/201606.html
Having 7-10 days off per month is not uncommon at all in that league. It may be that Japanese pitchers lose less games to injury and require less surgery than MLB pitchers because they have way more time to rest their arms. It may just be as simple a cause as that ... and may not have to with Japanese pitchers use of pronation breaking pitchers.
Major League Baseball is looking lately at trimming the schedule but they are looking into that not to save pitchers arms but to have the season finish earlier (to avoid conflicting schedules with other pro sports teams and to avoid winter weather during the playoffs). So even if they end up cutting the schedule down it will not translate into more rest days per month for pitchers.
It might save them a lot of arm injuries if they trim the schedule down from 162 games but still run it from April to October.
Alright so Yes pronation is still cool and, No the screwball is not more dangerous than other pitches. It is not an "arm killer" or "arm destroyer" in the least.
But, the case of Nippon League pitchers not getting injured as often as MLB pitchers may have more to do with how many off days they get per month to rest their arms and maybe is not because Japanese pitchers throw more pronation breaking balls than MLB pitchers do.
I know in the Winter Meetings MLB was looking to trim the schedule down from 162 games ... but their reasons were not for arm health and won't give the player more off days but would make the season finish in September instead of October. This move would not reduce any arm injuries therefore.
It would be an experiment to see if they do trim the schedule but still do the league from April to October ... give a few more off days per month ... and see if injuries and surgeries come down for pitchers' arms. I don't know how viable that is though ... but it may indeed reduce pitchers injuries greatly.