It doesn't matter why there is a new coach, fired or took a new job, most of the time the following year sees the record go down here is how it has played out the last two years!
COACHING CHANGES IN 2013
Team 2012 record 2013 record 2014 record
Auburn 3-9 12-2 8-4
Arkansas 4-8 3-9 6-6
Tennessee 5-7 5--7 6-6
Kentucky 2-10 2-10 5-7
Wisconsin 8-6 9-4 11-3
Purdue 6-7 1-11 3-9
Syracuse 8-5 7-6 3-9
NC State 7-6 3-9 7-5
Boston College 2-10 7-6 7-5
Colorado 1-11 4-8 2-10
Oregon 12-1 11-2 11-2
Cal 3-9 1-11 5-7
Texas Tech 8-5 8-5 4-8
NON Power 5 team
Team 2012 record 2013 record 2014 record
Cincinnati 10-3 9-4 8-3
So. Florida 3-9 2-10 4-8
Utah St. 11-2 9-5 9-4
Nevada 7-6 4-8 7-5
San Jose St 11-2 6-6 3-9
NIU 12-2 12-2 10-2
W. Michigan 4-8 1-11 8-4
Kent St. 11-3 4-8 2-9
FIU 3-9 1-11 4-8
La Tech 9-3 4-8 8-4
So Miss 0-12 1-11 3-9
UTEP 3-9 2-10 7-5
Idaho 1-11 1-11 1-10
COACHING CHANGES IN 2014
Team 2013 record 2014 record
Penn State 7-5 7-6
Washington 9-4 8-6
Vanderbilt 9-4 3-9
Louisville 12-1 9-4
Texas 8-5 6-7
Wake Forest 4-8 3-9
USC 10-4 9-4
NON POWER 5
Bowling Green 10-4 8-6
Wyoming 5-7 4-8
Army 3-9 4-7
Ga. Southern 7-4 9-3
FAU 6-6 3-9
Boise St. 8-5 12-2
Miami OH 0-12 2-10
E. Michigan 2-10 2-10
UAB 2-10 6-6
UMass 1-11 3-9
UConn 3-9 2-10
W. Kentucky 8-4 8-5
Ark St 8-5 7-6
Tell me what you see! Of all of these team I would say situation-wise Nebraska would probably resemble either Washington or Texas of last year or NC State 2013.
What do I see? I see zero relevance to our situation but let's look at your numbers.
First thing I see is that non power 5 teams do not belong on any list even remotely relevant to us. Usually, they have erratic W/L records year over year and, specifically, they universally have no claim to high quality replacement coaches. Good luck using anything from their records to explain what will happen here.
Secondly, for 2013 you listed 13 power 5 replacement coaches and of those...
3 were +/- 0 wins over the prior year
6 were -14 cumulative wins (14 less wins) than the prior year
4 were +18 cumulative wins (18 more wins) than the prior year.
Seven of the 13 had equal or more wins than the prior year - more than half of the new hires sustained or improved the prior year's win count. And the whole 13 totaled four more wins than the prior coaches had.
2014 more closely matches your point (irrelevant though it is). Here, you've listed seven new power 5 coaches...
1 was +/- 0 wins over the prior year
6 were -14cumulative wins (14 less wins) than the prior year
0 were + any cumulative wins than the prior year.
All in all, 2013 was a plus for new coaches and 2014 was a minus. This tell us nothing as 2013 could just as easily be replicated this year as not. The fact that 2014 could also be repeated is irrelevant as is the whole exercise. The fact that seven of these 20 new hires succeeded in their first year is all it takes to know it can be done.
And also, in each of these cases, local issues ruled the day. Louisville lost Bridgewater, Texas faced a severe cultural change, etc, etc, etc.