Smith, the Bengals' first-round pick in 2009, spent seven seasons in Cincinnati but signed with the Vikings during the 2016 free-agency period. He played only four games in 2016 due to injuries.
Terms: One year (financial terms undisclosed)
Grade: C. While bringing a veteran back could help, signing Smith is hardly a substitute for the two offensive linemen the Bengals lost in free agency.
The Bengals were clearly ready to move on after drafting tackles Cedric Ogbuehi and Jake Fisher in the first two rounds of the 2015 draft, so they obviously had no issue parting with Smith, whose season grades by Pro Football Focus have declined every year since 2012.
However, it's hard to assess where Smith is as a player now because his lone season away from Cincinnati was cut short by injury.
What it means: Smith was the Bengals' starting right tackle from 2011-15, so they're bringing in a guy who has familiarity with their system.
Smith could be a backup plan if Fisher and Ogbuehi struggle next season. Smith could also be a utility man who plays either tackle or guard.
Signing Smith doesn't mean he'll be a starter, as the Bengals would like to move forward with their two young players, but it does bring someone back who could quickly fit into their system.
What’s the risk: With Smith signing a one-year deal, the risk is minimal.
The risk depends on the Bengals' expectations. If Smith is expected to be a backup utility lineman who could potentially contend for a starting role, it's not a bad idea for the Bengals to see what he's got.
However, if Smith is already penciled in to start, particularly at guard where he has never made an NFL start, it might be a different story.
The Bengals' history of bringing back players is hit or miss.
Michael Johnson, Pat Sims and Wallace Gilberry all returned to the Bengals after stints away. Johnson signed a high-priced contract with the Buccaneers but was cut after just one season. Johnson returned to his starting role in Cincinnati, but hasn't come close to the 11.5 sacks he had in 2012.
Sims is a rotational defensive lineman, while Gilberry was signed midseason in 2016. Gilberry played in five games but sat out three games while injured. He had 2.5 sacks. He is now a free agent again.