According to advanced statistics-based preseason strength of schedule metrics, Ohio State has a slim margin for error if they hope to take a repeat trip to the College Football Playoff for 2015.
Football Outsiders' strength of schedule measure (from the new 2015 Almanac) has Ohio State's schedule as the 71st-most difficult in the country. The Buckeyes only have two games with Projected Win Likelihoods of under 91% -- against Virginia Tech (83%) and Michigan State (82%). Their Projected F/+, strength of schedule, and Projected Win Likelihood measures are based on a combination of advanced metrics, such as 2014 S&P+ and FEI rankings, Program F/+ (a long term measure), recent recruiting rankings, and departed NFL talent. Based on this data, Ohio State is seen as too talented and their schedule too easy for anything but an undefeated season or potentially a single loss to Virginia Tech to get them in to the Playoff.
Part of this is simply based on the fact that Ohio State is extremely talented based on the empirical data and statistical projections. F/+ adjusts for strength of schedule, but the Buckeyes are nonetheless ranked top in the country. But looking at the schedule, Ohio State only plays four teams next season that ranked in the Projected F/+ top 40 (adding Penn State and Michigan), and only two in the top 25. Of course, some teams will under and over perform (Minnesota could crack the top 40, while Penn State or Michigan could drop out), but based on the historical accuracy of the Projected F/+, it's difficult to imagine perceptions of the Buckeyes' schedule shifting dramatically over the course of the season.
Compare those numbers with its competitors for the Playoff. Alabama, at second in the Projected F/+, plays nine teams in the top 40 and has the fourth-most difficult strength of schedule. UCLA plays six teams in the top 40 and has the 40th strength of schedule. Even Michigan State plays five teams in the top 40, but has the 19th-most difficult schedule with an opportunity for a signature out-of-conference win over Oregon.
Even though Urban Meyer has yet to win a national championship and go undefeated -- and Saban has only done it once -- that doesn't mean the Buckeyes have any room for error, both because of the relative ease of their schedule and because early season losses hurt significantly less than late season ones in the eyes of the media and Playoff voters.
With Michigan State as the penultimate game and Virginia Tech as the first game, if the Buckeyes lose at all they would need to both do it against Virginia Tech then beat everyone else by a large margin to have any case for the Playoff. The suspensions would likely help if Ohio State does lose to Virginia Tech, but a loss would likely take the Buckeyes' Playoff destiny out of their own hands. A win over Virginia Tech but a loss to Michigan State is likely too late of a loss and likely deprives them of a signature win (especially if Michigan State beats Oregon). A loss to any other team likely plays out the same way, with both Penn State and Michigan towards the tail-end of the season, with no guarantee that either team will be top 25 material in the eyes of the committee.