The Chargers are clearly still in the market for a backup for Philip Rivers. Cardale Jones did not impress after being acquired via trade from the Buffalo Bills. And Kellen Clemens is an unrestricted free agent.
Geno Smith made one start in 2017 for the Giants. He was incredibly ineffective while ending the amazingly mediocre Eli Manning’s consecutive games started streak. The decision to start Smith contributed to both the head coach and general manager being fired.
Anthony Lynn may be a fan of Smith’s and he is certainly better physically suited to the type of offense Lynn likes to run than Rivers is, but Smith is also not any good. He has never been effective at the professional level and there is honestly no reason to think that is going to change in the future.