Summer is a time in college football where the only news is usually bad news. With that in mind, we're looking at the most indispensable players on each Big Ten team.

By indispensable, we don't necessarily mean best. We mean the players who would be hardest to replace between now and the start of the season if they got hurt/suspended/suffer from a grotesquely swollen jaw, etc. That could be because of their value to the team or because of a lack of depth at their position.

We'll pick two players from each team, usually offense and defense, but not always. Up next: the Northwestern Wildcats, who learned the hard way last year how tough it is to play without some of your most valuable players.

Brandon Vitabile, C, Sr.

Throughout a very rough 2013 season for the Wildcats, Vitabile provided some stability. He was an honorable mention All-Big Ten performer and team co-captain, and the redshirt senior has now started 38 straight games. Vitabile enters the season as one of the top centers in the league, and his leadership would be tough to replace on an offensive line that underperformed at times last season. Quarterback Trevor Siemian would also be a big loss on the offensive side, but Northwestern has some talented -- if very young -- options behind him.

Ibraheim Campbell, S, Sr.

The secondary should actually be one of the deepest and perhaps strongest units on the field for the Wildcats, who will return starters at all four defensive back spots. But Campbell is the most experienced and valuable player in the back end. His four interceptions tied for the team lead last year, and he provides major help in run support. Defending the middle of the field was an issue for Northwestern last year, and without Campbell, it would quickly become a major problem again.