Bradley:
It seems very hard to tell, at this point, what that original 9th green was designed like (from 1911-1916) not that that really matters to you, as the first photographic evidence of it seems to be when it was redone to essentially what we know it as and see it as today.
We do have a drawing from Flynn of it (which is not that much the way it became in 1916). At this point we can't really figure out why that was or even if Flynn's drawing may've been done by him a few years before we've believed he did it (in 1916).
But I think it's probably pretty safe to say that the most significant facet of the 1916 alteration is that they extended the green in the rear and brought up the rear of it (back to front) and also created that very prominent extension out to the left rear (which does not appear at all on the Flynn drawing we thought was from 1916).
As far as these reputed (and reported) "experimental mounds" that were mentioned in a 1913 article and seem to appear on that late 1912 photo posted on here----I think we need to look into the fact of those mounds just a bit more--or that everything surrounding that green in that photo was supposed to be that. At this point, I think it is certainly possible that what we see in that 1912 photo that we think are mounds (or some of it) may actually be sand pilled next to where they are preparing to dig out bunker cavities.
One reason I say that is some of it certainly is remarkably white and we need to appreciate that photo was taken at least a year AFTER that course went into its year long grassing (growing in) phase from Sept 1911 to Sept 1912 when it was first opened for play---at least reputedly. My point is why are some of those things that look like mounds that white over a year after the "grow-in" began on the course?
Actually Merion East may've been in a basic "grow in" phase until late 1913. I say that because initially MCC reported they would leave their former Haverford course when they opened the new East course in Sept 1912 but they actually kept the Haverford course open for play for their members until the fall of 1913. There must be a good reason for that app. 16 month extension and the continuing development and growning in of the East may be the reason.
Not to mention the fact that a few of the so-called "lower" greens on the East totally failed early on; they had to be rebuilt and the turf from some of the greens on the old Haverford course was stripped off, brought over to Ardmore and used on those early rebuilt greens.
Actually, at one point Merion (the Wilson brothers) had an entire green of turf trucked from Merion over to Pine Valley to returf the failed 8th green at PV!