These depth charts are fluid, and Hargrave might not take the first snap of the season, depending which coverage the Steelers run, but the fact Hargrave is sandwiched between Cam Heyward and Stephon Tuitt on the defensive line is significant.
The lineage of Steelers' rookie starters at tackle is not long.
You have to go all the way back to 1994 draft pick Brentson Buckner, now an Arizona Cardinals assistant coach under Bruce Arians, to find a draft pick who started Week 1.
That's at least 26 draft picks, including several first-rounders such as Cam Heyward, Casey Hampton and Ziggy Hood. There are many fun names on this list, such as Alemeda Ta'amu and Orpheus Roye.
McCullers has struggled to crack the lineup in the past, so maybe Hargrave had a quick path to start, but it's obvious he can play. Coach Mike Tomlin said Hargrave "routinely flashes" on the practice field.
Technically, the Steelers could have two rookie starters if the team opens in the nickel package and safety/corner Sean Davis is covering the slot, as expected.
A few other notes on the depth chart...
-- Jarvis Jones and Arthur Moats get the starting OLB jobs in light of Bud Dupree's place on Reserve/Injured. This is a crucial time for Jones in a contract year. Moats is a reliable option in this spot and finished the preseason with 1.5 sacks against Carolina.