It doesn't matter if you get Firas Zahabi, Robin Black, The Weasle, MMA GURU, Mighty Mouse, etc. Someone's always going to criticize their commentating. They're all going to say silly things live on TV. Some are going to focus on this aspect than that aspect, this fighter's gameplan instead of the opponent's, etc. Once they're gone, you can glorify Stann, Goldberg, or whoever you want, you can pretend you can do a better job. You can pretend Joe used to have it but has now lost it, whether due to age, drugs, money, lack of interest, etc. Lower the volume, play music, or listen to the Brazilian broadcast team if it makes you enjoy the spectacle more. As long as the fights are entertaining or gripping, it really doesn't matter. And if the fight is boring as all hell or full of illegal blows, bad ref, or bad judge scoring, it's not going to matter how good the commentators are. That being said, there aren't many former UFC champs who can either do better than DC and Dom or want the job in the first place, and the UFC is putting stock in the fans' assumption that former champs know what they're talking about at the top level of MMA more than 99% of humans.