Complex sentence: Under the advice of John D. Rockefeller, Jr., Maclaurin chose Rockefeller's personal architect and MIT graduate William Welles Bosworth to lead the next round of designs, in no small part because of his willingness to work for clients with strong personal convictions.
Split into simpler sentences: Under the advice of John D. Rockefeller, Jr., Maclaurin chose Rockefeller's personal architect, MIT graduate William Welles Bosworth, to lead the next round of designs. In no small part, he was chosen because of his willingness to work for clients with strong personal convictions.