Re: Goodwin Procter HQ (Parcel I) @ Fan Pier | 90 - 110 Northern Ave | Seaport
My guess, is that the extra concrete in that location was needed for reinforcement for the crane supports. Think about the way forces move, if the crane is performing a pick and the weight is acting to pull the crane in towards the building, those supports are going to be pushing outwards. If the extra concrete isn't there, then there probably isn't enough reinforcing to prevent the supports from breaking out.
They'll probably cut the opening to full size once the crane is dismantled.