Sometimes it doesn't work. Sometimes it does. Except for Milloy, however, all these guys have been here for the entire training camp, and minicamps, and had the playbook long before that.
Last year, Buffalo made a huge change by bringing in Bledsoe, two new offensive linemen, including a rookie, and played four offensive linemen at new positions. The playbook was changed completely because Buffalo brought in a new OC Gilbride, and scrapped the west coast offence that hadn't worked the year before, yet Buffalo came out at the start of the year on fire on offence. The fact that they cooled down later in the season had nothing to do with the ability of new players and new system to integrate, and more to do with the fact that late season weather is more difficult for the deep passing game and defensive coordinators learned that Buffalo's offence was not capable of the consistency necessary to sustain long drives when the deep pass was taken away. That was Gilbride's shortcoming last year. He didn't anticipate that happening.
Conventional wisdom is that early in preseason defences are ahead of offences. The rationale for that is it takes more time to grasp the complexities of the offence and timing issues between players are more critical for the offence. In theory that would suggest it should be easier for defences to get new players integrated than for offences to do the same.
Among the newcomers in Buffalo's defence, all four starters, are seasoned veterans. They won't be dealing with rookie jitters and probably will have an easier time integrating than rookies would.