The middle finger is a very strange place for wear so I am guessing a minor grip issue could be at play. Perhaps lighter grip pressure, it can cure MANY problems. Corded grips also wreak havoc on glove durability. Excessive wear on the thumb indicates that you could be extending your thumb to far down the shaft.
Also, are you hitting balls on the range in this glove that you wear for 5 rounds? You figure a near perfect ball striking round you will hit around 36 full shots with your glove on, for most this number will be well higher. A large bucket on the range can total over a hundred full shots, rapid fire, while you pour sweat into the glove. When you think abut it that way, one long range session is almost like playing three/four rounds of golf.