Ron Sargent, the interim CEO of Kroger and former CEO of Staples, just dropped $11.5 million on former Boston Celtics co-owner Steve Pagliuca's Back Bay mansion. The home, which had a listing price of $10.995 million, generated significant interest, receiving multiple bids, and went under contract within four days, according to a representative for George Sarkis, CEO and co-founder of The Sarkis Team at Douglas Elliman, who had the listing.