Pruitt is not getting fired.
Now saying that, I looked back over our schedule under Lane Kiffin, Dooley, Jones, and Pruitt. Here are my thoughts.
I hate to say it, Pruitt's performance looks the worse. A lot more losses to lower tier teams: (Georgia State, BYU, Kentucky, etc.). Pruitt's issue is obviously JG. Pruitt doesn't have a Tyler Bray, Jonathan Crompton, or Josh Dobbs.
Dooley's performance may be a little unfair. He had some decent wins, especially OOC. He caught the SEC when it was brutal. Most of the opponents he played against where in the top 10 (moreso than any of the other coaches on this list). Unfortunately, Dooley NEVER beat them.
Butch Jones had a couple of 9-4 seasons but he really didn't take advantage of the struggles of Florida and Georgia during his era. Both programs were down. Jones beat Georgia 2x but he really should have beaten Florida in 2014, 2015, 2016. Major choke job. Butch Jones had the easiest schedule of all the Tennessee coaches in that he caught a lot of SEC Schools that were down. Interestingly, Butch Jones brightest spots are OOC. He should have beaten Oklahoma in 2015, he beat Northwestern, Nebraska, Iowa, and Virginia Tech. He looks like the best coach since Fulmer but as stated, he had advantages the other coaches didn't have.
Lane Kiffin - In his one season, he has great wins of Georgia and South Carolina but bad losses to Auburn and UCLA (both should have been won). His bowl performance against Virginia Tech was ugly too. However, he got us competitive that season and was a FG away from beating Alabama.