Great question.
He got a pass in 2013, previous coach left him a stinking pile of crap for a roster, and we went 2-10
2014 and 2015 we improved quite a bit, 5-7 each year. But there were some critics (I was one at least to some extent). Blew a game against Louisville we had won in 2014 that would have put us in a bowl. Blew a game against Vanderbilt who had their usual terrible team that would have put us in a bowl in 2015, then blew a 21-0 lead at home to lose to Louisville, again. Offense was really bad in some of those losses which caused most of the issues
2016 is where things changed, but started off awful. Blew a 25 point lead against Southern Miss at home and took a terrible loss, then no showed at Florida, lost by a million points. I doubted he would make it to the end of the season.
But Stoops switched QBs (starter was injured), and went to more of a power running game, and slowly righted the ship. It completely turned around in the Miss State game, another home game we almost blew a double digit lead, but made a miraculous 51 yard FG on the last play to pull out a win. Then pulled the biggest upset in Ky history at Louisville (26 point underdog) against Lamar Jackson and company.
Since then, UK has capitalized on its improved play and continued to slowly, but steadily improve recruiting and overall talent. Anyone can see Kentucky today and see that we are way better talent wise than we were 10 or 12 years ago. And that is the biggest difference, just better players.
I personally do not think that Stoops is any brilliant tactician or game coach, but really is well grounded in fundamentals, blocking, tackling, create a solid running game that can consistently make first downs, don't make stupid mistakes, keep the ball in front of you on defense, don't give up big plays, etc. We are now 19-9 in our last one score games.
He has a great lead recruiter in Vince Marrow, and has changed offensive coordinators when it was necessary, Liam Coen will be hired soon by an NFL team or another good football school, has really made a difference in 2021 for sure.
Program is in a really solid place at the moment.