"The familiarity of everything, the routine I've gotten myself into, that's the biggest difference," Ertz said.
He was stuck in Palo Alto, Calif., last June when the rest of the Eagles tight ends were absorbing the beginning stages of Chip Kelly's offense.
General manager Howie Roseman talked last month about how that missed month affected Ertz's development. His production came mostly in the second half of the 2013 season. He had 22 of his 36 catches, 268 of his 469 yards, and all four of his touchdowns in the final eight games of the season.
The spike corresponded with quarterback Nick Foles' emergence and a five-game winning streak. There was more of an understanding of how Ertz would fit into Kelly's scheme, and the coaching staff had a better sense of how to use him.
"You saw in the second half of the season what kind of went on," Ertz said. "I was used all over the field."
When the Eagles drafted Ertz in the second round last year, they touted his versatility. He could play on the line, in the slot, and even split out wide. The versatility helped last season; he was the team's top receiving tight end, even though he played only 41 percent of the snaps.
With a no-huddle offense that will play even faster in 2014, it helps to have players who can be used in different ways. The Eagles like the idea of having a variety of interchangeable parts, with different sizes and skill sets, who can line up all over the field on a given play.
Ertz and running back Darren Sproles are two players who can be on the field on successive plays yet can line up in different spots.
"I think that's the biggest thing: You can't be subbing guys in and out with the [tight] ends we have," Ertz said. "We're able to do that [keep tight ends on the field], whether it's in-line or out wide."
One area of his game that he set out to improve during the offseason was run-blocking. Veteran Brent Celek played 77 percent of the snaps because he was a better blocker and able to contribute more in rushing situations. Ertz blocked on only 43.2 percent of his offensive snaps, according to Pro Football Focus. Celek blocked on 60 percent of his snaps.
Ertz and Celek are both playing on the line and on the move this spring, Kelly said. Kelly is also impressed with veteran James Casey, who is entering his second season with the Eagles but was used sparingly for much of last season. Ertz is the one with the most upside, though. His first offseason program will be beneficial and is likely to help him get on the field more in 2014.
"Receiving has come more natural to me in the past," Ertz said, "but there's an emphasis on the blocking this year."