Jim,
Did you ever wonder why they didn't locate the 14th green along the quarry? It certainly would have made for a dramatic and scary approach.
Although my drawing is crude, and I've probably got it a little close for comfort, it would have been very easy for them to get those last holes in that available width if not for the design decision to provide an alternate fairway route around the quarry.
You'll notice that all the land I've saved...coincidentally is the land that bulges out of the difference between today's course and that November 1910 Land Plan.
Interestingly, we saw a very similar thing when Wilson and his friends designed Cobb's Creek. On their original proposed map they had located the 6th hole very close to a steep dropoff that ran from the fairway landing area all the way up to the green. Along that hole to the left were three holes that ran perpendicular to the 6th, being the original 8th, 9th, and 11th. On the original map they were roughly estimated to be 420, 430, and 570, respectively.
When built those holes were only 387, 400, and 513. What happened?
Well, it wasn't until we later superimposed an "as built" over the original topo map that we determined that the 6th actually had to get moved further left than drawn. Perhaps the ground over there was too sloped and there wasn't enough room to keep balls in play...perhaps they ran into some issues with tree removal, as they had to work around existing trees.
Whatever the reason, they had to make a decision in the field that led to them moving the entire 16th fairway and green left of what they originally proposed, and that had unintended consequences for adjoining holes. In the case of Cobb's Creek, they were working with a fixed acreage, so they couldn't do anything but shorten those holes.
I think something very similar is what happened here. Design decisions, probably once out and dealing with the reality of what was on the ground and not on paper forced them around the quarry, which then forced other holes to be taken out wider than was originally anticipated/planned, which then required adjustments of land between golf and real estate, as well as the addition of 3 acres. Cobb's Creek didn't have the option to expand their acreage, but Merion...through Lloyd, did.
One last point from the dead horse. The MCC minutes speak of swappoing land for other land "adjoining". I'm not sure I'd refer to the triangle in that way, would you?
Conversely, if one is to take Francis as meaning they only added the triangle of land in the swap, you have to believe that Merion located their first 13 holes, including using up one par three on the back nine across from the clubhouse, and then were going to try and fit their last five finishing holes in this acreage. That to me indicates that they'd have to be insane, as well as purposefully ignoring CBM's good advice in June 1910 that much could be made of the quarry.