The tight end spoke glowingly about teaming up with Smith, who spent the past five seasons with the Kansas City Chiefs while Davis bounced from the Denver Broncos to the Washington Redskins after his 49ers tenure ended in 2015.
"He's been taking off," Davis said this week, via ESPN. "His game has elevated dramatically. I say that because of his ability to get in and out of the pocket, he's getting the ball downfield, he's just placing the ball where it needs to be and he's doing it effectively.
"He's only getting better. He is going into his 14th season, and to see him playing the way he's playing is unbelievable."
Davis was drafted No. 6 overall in 2006, a year after the Niners used the No. 1 pick on Smith. Davis enjoyed his best seasons with Smith as a starter, earning 965 yards and 914 yards in 2009 and 2010 respectively.
The 34-year-old Davis has lost a step with age but played a key role in Washington's offense last season with Jordan Reed injured (again). Davis believes Smith can bring playmaking and consistency to Washington's game plan.
"His ability to get in and out of the pocket, keep the play alive," Davis said. "That's going to be tremendous for us, and it's imperative that we have that because, you know, this game is all about how effective you can be, and if you can sustain plays, then that's good, that's great, because that allows the receivers to get open when everyone else thinks the play is dead and we can still keep going."
Davis said Smith has evolved from the quarterback he was during their San Francisco tenure.
"I watched Alex go through so much," Davis said. "His career was so turbulent with so many offensive coordinators and he had years where he wasn't doing well, and then he had years where he started to excel. So he's been through a lot. To watch him get better after he left, his game started to evolve right before he left San Francisco.
"I mean, this guy, he is at a different level right now. He is playing as an elite quarterback in this league, and it's great to see that, it's great to see his career, the way it started to where it is now."