Prove it? Lol He maybe was a okay HC, but he was most definitely a great position coach and coordinator. Men lie, numbers don't.
"For the 2004 season, he added the duties of passing game coordinator, and he was promoted to offensive coordinator for the 2005 season after Norm Chow left USC for the same position with the NFL's Tennessee Titans. Kiffin also took the reins as recruiting coordinator that year. Along with these duties, Kiffin continued as the wide receivers coach. Under Kiffin in 2005 the USC offense produced numerous school records, averaging 49.1 points and 579 yards per game and becoming the first in NCAA history to have a 3,000 yard passer (Matt Leinart), two 1,000 yard rushers (Reggie Bush and LenDale White), and a 1,000 yard receiver (Dwayne Jarrett). Steve Smith fell a few yards of also surpassing 1,000 yards in receiving."
"In Kiffin’s three years as recruiting coordinator at USC, the Trojans had the No. 1 ranked recruiting class in college football every year. The Trojans finished first in the Pac-10 in passing efficiency by averaging 142.8 passer rating, produced two, 1,000-yard receivers – Dwayne Jarrett (1,105) and Steve Smith (1,083) – and a 3,000-yard passer John David Booty, with 3,347 yards. The team produced top 20 statistics in most NCAA offensive categories and concluded with a 32–18 win over the then #3 ranked team the University of Michigan in the Rose Bowl."
"Kiffin helped guide USC to a 23–3 win-loss record during his tenure as offensive coordinator, an 88% win percentage; however, in June 2010 the NCAA retroactively declared Reggie Bushineligible for the entire 2005 season, and forced USC to vacate all of its 2005 wins. Litigation from former coach Todd McNair to overturn those vacancies is still ongoing."
http://en.wikipedia.org/wiki/Lane_Kiffin
Again, he was a great position coach and coordinator. And to be honest, I don't think he was that bad of a HC. Look at the raiders for example, they haven't been a great team since 2001 when Callahan took the team to the playoffs. Since then the Raiders hired "5" different coaches and Lane Kiffin was one of those 5 coaches. That goes to show that the Raiders is a tough place to win at. Also, Lane Kiffin was only 31 years old when he was hired as the Raiders HC. The youngest HC in NFL history, and that was his first HCing job, so I wasn't surprised that he wasn't successful there. At Tennessee Kiffin's team went 7-6 after phillip fulmers team went 5-7 the year before.
"Kiffin led the Vols to a 7–6 record in 2009, an improvement from their 5–7 record in 2008. The Vols increased their offensive output by more than 60 percent in 2009 with Kiffin calling the offensive plays.[23] Highlights included wins over South Carolina, Georgia and Kentucky. However the season was marred by losses to UCLA, Florida, Auburn, Alabama, and Ole Miss, as well as a 23 point blow-out loss to Virginia Tech in the Chick-fil-A Bowl. After one season as coach, Kiffin left the Vols during the 2010 recruiting season to accept the head coaching job at the University of Southern California."
Kiffins 2011 team went 8-5 and the 2012 team went 12-2 in a league that host Oregon, Stanford, and Washington.
So to say he's a joke is ridiculous, but I guess you're entitled to your own opinion. Once again, numbers don't lie. You can say all you want but he is a great coach.
He may not be a perfect human being as you may think you are, but he is a great coach.