Walker had been through the club academy, he'd trained with the first team squad for a season, and had plenty of support/contacts throughout the club.
Taylor had none of this. Plus I'm one of the fans who think Walker while a good player and talented was far from faultless last season, getting caught numerous times in possession which lead to goals, or rashly diving in when out of position. This was with the support system he had in place at the club, Taylor was new to everything and had to settle.
In fact reading on SEB seems to have summed it up.