I wasn't sure about starting a new thread on this, but I'm currently reading an ESPN article about Tommy John's and "epidemic".
Fairly good so far, talking about younger kids and pressures on teenagers to get to those showcases.
http://espn.go.com/mlb/story/_/id/12842678/why-tommy-john-surgeries-cease-soon
The one thing I've taken away so far is the want of the scouts at the showcases for the pitchers to throw as hard as they can for an inning or two, even if they aren't in game shape, due to the timing of the showcase.
I had a similar parallel, as I went to an open tryout during my final year of college. I had played my first 4 years, but year 5 I was coaching as my eligibility was up. I was pitching, and while no where near elite, I was fairly decent.
However, my last game playing time was in a senior league in August and this tryout was in March, in Winnipeg, so it wasn't warm. It was more of a whim thing that Dad figured might be a good idea. He took me and a couple guys from our summer team there and it was basically, throw 15 pitches as hard as you can. They didn't care if you could get guys out, just looking for speed. That wasn't my up my alley as I topped out around 85.
15 pitches to have a long outside shot as getting invited to spring camp with the team.
I didn't feel bad pitching that day in March, but when it came time to play with my summer senior team for the last time, my shoulder was fucked.
I pitched hurt all summer and was not effective. Giving up way to may 0-2 hits, because I didn't want to waste a pitch due to the pain.
It's now 11 years later and the shoulder doesn't feel to bad these days, but I'm pitching BP to 9-11 year olds as well.
I've played slo-pitch all the way through and up until the last couple years, the shoulder always hurt whenever I needed to put something extra on a throw.
So I can definitely see how these showcases and other pitching in high school and travel teams would be really bad for kids and prospects.