Rob ( @FlatGround / PitchingNinja ) is too modest. He's one of the most influential guys in the baseball Twittersphere right now. His platforms have provided exposure to many thousands of players at all levels.
My son was in the portal a couple years ago, looking to transfer out of a D2, and Flatground retweets gave his videos over 10,000 views. As a result he gained probably a hundred coaches following him, and this led to direct contact with the majority of these coaches, and certainly had an influence on his transfer to a D1 program.
Point being - that his stuff not only benefits the top-level pro caliber guys (who would likely eventually be discovered anyway,) but he is providing tremendous exposure to kids at all levels.