I disagree. Koeman is a better tactician than Moyes and his philosophy isn't too dissimilar to that of Pochettino. No major overhaul in tactical discipline would be expected from Koeman, that's for sure. Moyes on the other hand would be a dramatic culture shock down there. Southampton fans have gotten used to good football, it'd be criminal of them to employ a dinosaur like Moyes.
Then there's the average age of Feyenoord's squad that Koeman got into the Champions League with this season. He's worked wonders with the likes of de Vrij, Martins Indi, Clasie, Boetius, Vilhena and even Kongolo. In fact, Southampton and Feyenoord's academy structures aren't too dissimilar from each other. Koeman would thrive in that sort of environment. The same can't be said for Moyes. Can you honestly say that he embraced our academy while he was with us?