On paper, Dickstein Shapiro, the 61-year-old Washington law and lobby firm, had a difficult year in 2013. It experienced a 20 percent drop in revenue and a 35 percent drop in profits, declines that even in a challenging market for corporate law firms are considered sizeable. Since last summer, dozens of attorneys and professionals have left to join other law firms, including clusters that went to Crowell & Moring, Greenberg Traurig and Lowenstein Sandler.