So in my usual fanatical way I deep-dove into videos of other "great" pitchers. Man I found most that slap their leg. Scarborough, Nelson, Finch, Mowatt, to name a few. I finally found Lawrie that didn't. (she's pretty good too... :-) )
In conclusion I think the final answer for us needs to be that I gotta watch my DD's health and make sure that she is not permanently damaging her wrist or leg but other than that it might not matter too much.
To be honest, when I saw the other top pitchers do it the way my DD does it I am resisting the urge to try and change. My DD's glove hand is almost exactly like Scarborough.
I did go out and put in an order for a McDavid 6440R Knee pad, in the XL size, to be pulled up to the thigh level.
I can update ya later on that yet one more additional purchase for the DD :-)
Detail that I forgot to mention is that once she gets into the season it appears that the leg gets "tougher" and bruises less. It's just the beginning of the season ramp-up that can get her thigh really ugly lookin. She did have a 350 pitch weekend though last year that got painfull too though.... (this will stay current in my head ;-) )
I believe that as fastpitch became a much bigger sport at the younger ages for girls that's when the "fathers" got involved and started tinkering with everything. I am being critical of a lot of the fathers. I see it all of the time. That's how a lot of things that go on today with the girls got so out of whack. The 9 pitch comment I made is certainly a problem when developing pitchers. I believe that one is definitely the result of daddy looking for the edge for his daughter and making sure she can throw all kinds of pitches when in fact she should concentrate on 2 or 3 at the most.
More often than not, those conversations about the 4+ pitches an 11yo allegedly has are more about bragging than about any perceived edge a pitcher would gain.
Come to the fields in NorCal. Many of the biggest offenders when it comes to tinkering are mothers and they get in heavily on the bragging game, too.
One thing is certain, though: if there weren't as many 'fathers' involved as there are today, there wouldn't be nearly as many opportunities for girls to play softball.
Not all Bucket Dads are the problem either. I have seen and heard of just as many clueless coaches telling 11yo they cannot pitch if they do not have xzy pitches. I have seen coaches call a rise ball for an 11yo (that was just a high pitch). Many PC's will cave to the requests of parents (who do not know any different) that are caving to the requests of coaches.
As much as one can blame fathers for tinkering, one can also blame coaches.
Many parents do try to educate them selfs for the protection on their DD. This site has been great for me, and by proxy for my DD.
Most coaches are just parents, or at least started that way.
Fortunately, these days there are plenty of great programs, learning, and training opportunities available to anyone with an open mind, a bit of cash, some time, and willingness to learn so that they can be informed students of the game instead of boneheaded maroons blathering nonsense to a bunch of impressionable kids.
Unfortunately, being a blathering boneheaded maroon seems to be the "in" thing (along with a disgusting pot belly) amongst softball "coaches". Luckily trends change.