All valid points which I am in agreement with. The thing with Diaz in terms of the OP's question is that while he has had some very bad and well documented bumps in his tenure as HC so far he has also shown the ability to recognize his mistakes and shortcomings and address them immediately. After the disaster that was the 2019 season(6-7) he quickly realized that Dan Enos was a tremendous liability and pulled the plug after 1 year. He responded by hiring OC Rhett Lashlee along with WR coach Rob Likens and OL coach Garin Justice. It is interesting to note that both Justice and Likens had prior OC experience. It was also obvious that we sorely lacked leadership, maturity and the abilty to consistently make plays at the QB position. Enter D'erique King.
This past season in 2020(8-3) the offense was able to improve drastically despite spring practice and the majority of the off season getting wiped out due to Covid. King was as advertised for the most part and brought leadership, maturity, consistency and stability to the offense. Despite this, the defense seemed to take a huge step backwards. It was obvious that the level of coaching on that side of the ball was severely lacking. Now whether or not Diaz had anything to do with DC Blake Baker and Co-DC and safety coach Banda leaving for other opportunities is something that is up for debate. There were also new openings for DL coach and CB coach. Diaz reached out to and hired very highly regarded DB coach and elite recruiter Travaris Robinson to coach DBs and promoted Demetrius Van Dyke to coach CBs and learn under T.Rob. Diaz brought back Jess Simpson as AHC/DL coach and brought in Bob Shoop who has been a very successful DC as a defensive analyst. Diaz also grabbed Travis Williams from Auburn to coach LB but that was short lived as T.Will was offered and took the DC position at UCF. Diaz then finished off the upgrades to the defensive staff by bringing in energetic and elite recruiter Ishmael Aristide from Texas A&M to coach the Striker position. Lastly Diaz announced that he himself would be taking over full time DC duties in addition to being HC.
In addition the latest recruiting class 2021 was excellent and worthy of a top 10 ranking. Diaz went into this while thing knowing that he would be learning on the job. Diaz was hired despite never having been a head coach and it most certainly showed out of the gate. I do think that all of the criticism levied at him is mostly justified but I also have to give him credit for showing the desire and the ability to recognize his mistakes and rectify them in addition to showing improvement along with the potential to keep improving. Diaz has shown to be a very good judge of what the team needs to change/address in the off-season in order to take another step forward. Over the course of 2 seasons, Diaz has recognized the initial mistakes he made in hiring his initial staff and with the exception of coach Field and coach Hickson he has completely revamped the entire staff and filled both sides with proven, experienced and quality coaches who can also evaluate and recruit at a very high level. It should also be noted that other than Diaz and Lashlee this staff has 4 other coaches who have prior coordinator experience.
To finally answer the OP's question, yes, I think that Diaz has it in him to improve to the championship level. That opinion may be in the minority but it is my opinion nonetheless. I'll also add that one year ago I would have had a completely different opinion. On top of that I have never been shy about criticizing or outright ripping Diaz. What he has shown me over the course of the past 2 seasons is that he is very aware of what the teams weaknesses are and the willingness and ability to correct it. Then this past off season with the hiring of Bob Shoop, Diaz finally showed me that he is aware of his own weaknesses and that he is willing to improve on and tweek his own defensive system. Shoop isnt coming here to be anyone's puppet. Now what we need to see is improvement in Diaz with regards to game day coaching and I think that he can and ultimately will.