Cubs’ apparent budgetary constraints stress need to find Next Big Thing

For all the new faces, packed ballrooms, countless autographs and hours of banter between fans and Cubs people, the big thing about the Cubs Convention this year was, well, The Next Big Thing. Whatever it turns out to be. It’s what president Theo Epstein was brought in to identify, what is at the core of his staff’s efforts to redefine the Cubs’ baseball operations and what is likely to justify or deflate the three-day gush of hype and hope at the Chicago Hilton and Towers during the weekend. ‘‘It’s always there, looking for that next frontier of competitive advantage,’’ said …