It is funny. While I see lots of people taking pot shots at the 128 rule, which determines the LSA, I have yet to see anybody prove that it doesn't work: by grinding a cam using 128 & then using cams with identical parameters except for LSA....& dyno testing/comparing them.
The problem is that the LSA is just seen by many as a number. It is just a number, right?
It is much more than that....
It tells you in crank degrees where max lift occurs. For a 106 LSA, it tells you that the intake valve is at max lift at 106* ATDC & the exh valve at max lift 106* BTDC. Max lift, & either side of it, has to be an important parameter, especially for the intake side, because that is where maximum airflow happens. No air in = no hp.
The other important parameter is piston speed...& that is related to crank position ...which is tied in with LSA. More piston speed, more air 'pulled' into the chamber, all else being equal.