BOSTON -- David Ortiz thinks he knows why the Chicago Cubs haven't been able to win consistently.

Ortiz, who stands as Theo Epstein's biggest acquisition during the Cubs president's decade as an executive with the Boston Red Sox, blames the one thing many Cubs fans cherish -- the one thing that sets the Wrigley Field experience apart.

"Through the years I've talked to a lot of friends of mine that have played for the Cubs," Ortiz said Tuesday night before the Red Sox lost 2-1 to the Cubs in the second game of a three-game series at Fenway Park. "The one thing that everyone talked about was the schedule in Chicago. They get excited walking into a city that's based on baseball, but once they start dealing with the schedule it kind of mentally wears you down."

Ortiz cited former Cub Alfonso Soriano among others who haven't liked the mixed schedule of day and night games.

When the team first installed lights in 1988, the Cubs were limited to 18 night games due to their stadium being in such close proximity with the neighborhood. Over the years the city had increased the number to 30 and for the first time in 2014 the Cubs have 38 scheduled night games.