Honestly the one Hitting Instructor I'd like to see is Rod Carew.....Carew was almost a Yankee, in a deal that feel thru decades ago. Carew has a lasting impact on any and all Player's he worked with as Hitting Coach for the Halos, and Brewhahas. Although Carew had a public hitting school in the Inland Empire of LA, he gave my own son the traditional 8 week one on one, (with additional film studies of each public kid, he tutored). I watched numerous Little Leaguer's, American Legion, and High School kids, gain a "On Fire", yet patience approach, enabling every single kid, I watched Carew give instruction too, in 88.
My own son, had a .342 Batting Avg, as a JR. in High School. As the next HS baseball season came, Joshua, let the local HS League with a unbelievable .429 Batting Avg, on the year. He also doubled his walks, RBI's, Doubles, Hits, you name it. Carew is the only soul, who pays dividends in his instruction. 
Carew the one who got away and almost made it in trade to Pinstripes, but then what would of became of Donnie BB???
HooYah, YowZa, Carew the King of Swat, and place hitting....none better IMO, in his day....Yeppers...,!