Two players he doesn't have to worry about, though, are place kicker Steve Gostkowski and punter Zoltan Mesko. Gostkowski made 28 of his 33 kicks last year (the most he's made since 2008, when he hit a career-high 36). Mesko averaged 46.5 yards per punt, 11th in the league.
“They go out every day to get their work done,” O'Brien said. “Nobody's ever, every good enough. There's always something that they're focused on. If we come off the field one day and there's something we notice technique-wise that we weren't doing correctly, that becomes the emphasis the next time we go out there.
“But they go out every day to get better, they're pretty good self starters. They know what it takes. They know where they're at. Physically, they're in good shape. They're getting their timing, they're getting their rhythm and trying to improve every single day.
There have been some curveballs in the early stages of camp. On the second day, Aaron Hernandez was back catching punts. On one attempt he looked like an outfielder who lost a fly ball in the sun, calling for fair catch but having to race desperately to yard ahead of him to get under it. O'Brien said the drill helps.
“Any time you're a ball handler, one of the hardest things to do is catch punts. It's not only a great drill for any receiver – as well as punt returners – to focus in on trying to catch a ball that's normally tougher to catch a quarterback throwing that ball.”
Returning punts requires a certain skill set, O'Brien said, but the process of become a good one takes time.
“There's confidence obviously,” he said. “It's like having to run through a door and you don't know what coming through the other end.
"There's a learning process with all returners no matter what experience they've had in the past because of the schemes. It's a learning process besides the physical skills they do have."