Why? Penn State has had Michigan and Ohio State back-to-back around a dozen times. How often has either of Delaney's darlings faced a power opponent prior to their love fest?
PSU played them back-to-back in '93 and '94, but had a bye week between the two games each year, so I wouldn't categorize those as back-to-back games. After those seasons, the years in which PSU played Michigan and Ohio State (in whichever order) in back-to-back games were:
2005
2008
2011
2013 (again, a bye week between the games, so I wouldn't include them as back-to-back games)
2014 (again, a bye week between the games, so I wouldn't include them as back-to-back games)
2017
So the PSU played tOSU and Michigan in back-to-back games (without a bye between them) 4 times in 26 seasons. That doesn't seem excessive, or all that unusual.
How does it compare to tOSU and Michigan.
tOSU - years when they played PSU and Michigan (in whichever order) in back-to-back games where there wasn't a bye between the games:
2011
So tOSU has played PSU and Michigan in one back-to-back game since PSU joined the B1G.
Michigan - years when they played PSU and tOSU (in whichever order) in back-to-back games where there wasn't a bye between the games:
1995
1996
1999
2000
2015
So Michigan has played PSU and tOSU in five back-to-back games since PSU joined the B1G.
Before B1G went from 11 to 14 teams, there were some years where Michigan rotated off of PSU's schedule, whereas tOSU was always on PSU's schedule.
There's also the issue of tOSU - Michigan always being the last game of their respective regular seasons, whereas the PSU playing either team can take place in any week where league competitions take place.
So if you look at the big picture, in the years since PSU joined the B1G, Michigan has played tOSU and PSU five times in back-to-back games, PSU has played tOSU and Michigan four times in back-to-back games, and Ohio State has played PSU and Michigan one time in back-to-back games.
It doesn't appear that anything is out of order in the number of times that Michigan has played the other two teams in the discussion in back-to-back games, or in the number of times that PSU has played the other teams in the discussion in back-to-back games. The only outlier is Ohio State only playing the other two teams in the discussion one time in back-to-back games since PSU joined the B1G.