Pretty obvious to me that he's never been especially comfortable within punching range. I guess you can say it's due to a deficiency. Anderson seemed to get the better of the exchanges when he closed in despite, frankly, being careless. But Izzy didn't have the 1 foot height and 8 inch reach advantage that he has over the majority of guys so he couldn't play the lean and hook game like he did with Costa and Whittaker.
Or maybe Izzy just thinks it's not worth the risk and would rather reset and tee off on dudes with kicks. He is the certified master in that area after all and if you can beat a guy by playing it safe then why not?