PITTSBURGH -- He still uses his GPS to make his way around Pittsburgh, but rookie inside linebacker Ryan Shazier didn’t need nearly as much navigational assistance when he was on the Pittsburgh Steelers practice fields in late May and June.

Shazier started alongside Lawrence Timmons from the outset of offseason practices, and he looked anything but lost despite learning a new defense on the run.

“He understands concepts very well,” linebackers coach Keith Butler said of the Steelers’ first-round draft pick. “He reminds me a lot of Larry Foote in terms of football intelligence, and he’s a very sharp guy.”

Not that Shazier will be exempt from the requisite rookie growing pains. Or that Butler wouldn’t prefer the Steelers easing the former Ohio State All-American into the NFL.

That is not an option in large part because Shazier’s speed and playmaking ability are both badly needed on a defense that slipped appreciably last season. Shazier, the Steelers’ most significant addition during the offseason, made it look easy at times during offseason practices. He turned in a couple of breathtaking plays, including a leaping interception of a pass that backup quarterback Bruce Gradkowski thought he could throw over Shazier in the middle of the field.

The caveat with how good Shazier has looked: the 6-1, 237-pounder has only practiced with the Steelers in shorts. That changes Monday, when the Steelers don the pads at training camp following two non-contact practices.

If Shazier makes the same kind of progress at camp as he did during offseason drills he will start Sept. 7 in the season opener against the visiting Browns.

Here are the four other significant additions that the Steelers made during the offseason.

Offensive line coach Mike Munchak. The Steelers have too often fielded suspect offensive lines under coach Mike Tomlin, though constant injuries up front haven’t helped. A line that came together in the second half of last season will start a pair of former first-round draft picks and two second-round selections. Nobody is more qualified to bring the group together then Munchak. There are no excuses this season -- unless mass injuries consistently scramble the line.

S Mike Mitchell. As with Shazier, the Steelers added speed and a playmaker when they signed Mitchell to a five-year, $25 million contract in March. They badly needed both elements on the back end of their defense, and Mitchell will be a significant upgrade over Ryan Clark at free safety. He has aspirations of becoming one of the best safeties in the NFL, and the Steelers would love to see Mitchell achieve that goal in Pittsburgh.

RB/WR Dri Archer. The Steelers added a bolt of lightning to their offense when they drafted the ultra-fast Archer in the third round. He will return kickoffs and could allow the Steelers to relieve Pro Bowl wide receiver Antonio Brown of his duties as the primary punt returner. Archer’s speed and versatility gives offensive coordinator Todd Haley the kind of player he can use to exploit mismatches. If Archer is Chris Rainey 2.0 the Steelers will be more than happy with the investment they have made in the former Kent State star.

OLB Arthur Moats. The former Buffalo Bill has starting experience and versatility and gives the Steelers a promising option should there be injuries or ineffective play at outside linebacker. Moats can also play inside, though the Steelers are pretty deep there, and he is expected to establish himself as a core special-teams player. The importance of depth in the NFL can't be overstated, and the Steelers improved themselves in that area with the signing of Moats.