Jamie,
That is not a Flynn bunker, nor is it a Flynn green on the 14th hole at Huntingdon Valley. Donald Ross came in Oct. 1946, after Flynn's death, and submitted numerous changes to Huntingdon Valley. This is one of the few changes that were accepted. Flynn's green site was to the right of this green about 40 yards or so near the creek. The reason for doing this was to allow for a back tee that lengthened 15. The back bunker on this hole was, I believe, built by the superintendent at the time. I don't think it is very Flynn-like although the green certainly is with multiple bunkers in the hillside on one flank and a single bunker green level on the other flank. When Flynn had a back bunker (original back bunker on 1 and 5 at Merion East) they were flat-bottomed but not flashed so high as it is in the overly-manufactured mound at the rear part of the HVCC bunker. Ian Andrew doctored a photo of this green taking the bunker out. I'd be curious to know what you think, I liked the look. I wish I could post the picture--my computer limitations are evident. Perhaps Ian will see this and post it. Or, I can email you the picture if you'd like.
Regards,
Wayne