Speaking Friday to the Wisconsin athletic board, Alvarez said Big Ten commissioner Jim Delany wanted to add teams in the Northeast to ensure Penn State would remain in the conference.
"Jim felt that someday, if we didn't have anyone else in that corridor, someday it wouldn't make sense maybe for Penn State to be in our league," Alvarez told the board, according to the Milwaukee Journal Sentinel. "That they would go into a league somewhere on the East Coast. By doing that, it keeps us in the Northeast corridor."
The Big Ten added Maryland on Nov. 19 and Rutgers on Nov. 20.
Delany described the moves to ESPN.com as "an Eastern initiative with a Penn State bridge." Delany said in a text message to ESPN.com on Friday that he doesn't want to comment on what others are saying about the expansion rationale.
Asked last month whether he had any concern about losing teams from the Big Ten, Delany said, "No. Not in my view. But I do think that you need to build, and this build really solidifies the expansion we've done in the past. We've done one in the East, we've done one in the West [Nebraska in 2010]. I would say the driving force is demographics, but when you look at it, you can't help but think this is good for Penn State as well."