Such pre-draft workouts are nothing new for top quarterbacks, even for teams that appear to have little chance of picking high enough in the order to land somebody of Mariota's caliber. That said, there is a little bit of intrigue going on in San Diego.
Current starting quarterback Philip Rivers has indicated his intent to play out his contract with the team, due in part to the potential relocation of the franchise to Los Angeles. There has been increasing speculation that such a statement has led to the team's front office looking into trade partners and the one that has been mentioned the most often is Tennessee.
The Titans, holders of the No. 2 overall selection in the draft this year, certainly would be keen on landing a starting quarterback and a trade for Rivers would reunite him with former Chargers offensive coordinator Ken Whisenhunt. If the clubs were to agree to some sort of trade package, that would present the scenario where the Chargers wind up with the No. 2 pick and end up selecting Mariota as the team's quarterback of the future.
Who knows what will end up happening when the clock starts ticking on the NFL draft in Chicago, but it seems pretty clear that the Chargers are one of the teams who are doing all of their homework on the Oregon quarterback just in case the opportunity to pick Mariota presents itself.