I'm not buying this "he is too short" nonsense. Poona Ford has freakishly long arms, his wingspan is 80 freaking inches. Having long arms allows him to keep OL's from getting into his pads and he can gain better leverage than the OL more often than not. Him being short and powerful IMO gives him a center of gravity advantage and probably a bit more quickness and explosion.
Typically coaches prefer taller DT's to bat down passes and disturb the QB's vision but i think when you have a guy built like Poona who can get great penetration up the middle, the height stuff goes out the door.