The tight end missed all of the organized team activities (OTAs) prior to his rookie season because he hadn't graduated from Stanford.
Ertz wound up registering 22 of his 36 receptions and all four touchdown catches in the second half of the season.
Ertz is expected to have a bigger role in 2014 and it's showing through OTAs and the three-day mandatory minicamp, which concludes Thursday.
"I've had a relentless work ethic this offseason," Ertz told the Wilmington (Del.) News Journal. "I just want to get better every day. That's been the focus."
Ertz had 469 yards receiving and improved steadily as a blocker through his rookie season.
"He's got a lot [of tools]," tight ends coach Ted Williams told the News Journal. "He's an excellent route runner. Guys that big and run that well and have the skills and tools to be precise -- body control, strength, size, leverage -- I think they're different. There aren't a lot of them like that. Not at his position. You saw the Shannon Sharpes of the world, the Ozzie Newsomes of the world who can do those kinds of things. That made them premier players."
Brent Celek finished with 32 receptions for 502 yards and six touchdowns and formed a strong one-two punch with Ertz.
"We run the ball a lot, so in this offense, a good blocker [at tight end] is a necessity," Williams told the News Journal. "If he can't block, we can't run the ball. And if we can't run the ball, we won't throw it very well. So it's important in this offense that we understand … that has equal importance to the other skills. The more tools you give him to put in the toolbox, the greater opportunity he should have to execute them."